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A domestic water heating system that combines photovoltaic thermal (PVT) solar collectors with two heat pumps, in a novel cascade arrangement, is presented and analyzed in this paper. The goal of this analysis is to determine and compare the annual thermal energy output of the PVT cascade heat pump system with an evacuated tube and simultaneous consumption PVT single heat pump water heating system. The computational technique that was developed to analyze the PVT cascade heat pump system, which determines solar panel energy outputs, and heat pump operating characteristics, is described in detail. Case study simulation results are also presented, which include transient power output profiles, temperature profiles, and yearly energy output results. Hourly weather data, including air dry-bulb temperatures and solar flux values, from locations with a range of climates was used in these simulations. The results of this study show that the PVT cascade heat pump system has an annual thermal energy output improvement over the evacuated tube heating system ranging from 37% to 68%, depending on the selected simulation location.

A large share of the primary energy is consumed to provide space heating. Geothermal energy offers a regenerative alternative. For reasons of efficiency and environmental protection, it is important to ensure the system integrity of a borehole heat exchanger (BHE). Previous investigations have focused on the individual components of the BHE or on the grout and pipe systems’ integrity. This study focused on the analysis of the hydraulic system integrity of the complete subsoil–grout–pipe system as well as possible thermally induced changes. For this purpose, a pilot-scale experiment was built to test a 1-m section of a typical BHE under in situ pressure, hydraulic and temperature conditions. During the tests the hydraulic system permeability of the soil and the BHE was measured continuously and separately from each other. In addition, the temperature monitoring array was installed in a 50-cm cross-sectional area. Significant temperature-related fluctuations in the sealing performance could be observed. Hydraulic conductivity limits required by VDI 4640-2 (Thermal use of the underground—ground source heat pump systems, 2019) were exceeded without frost action. The succeeding application of freeze–thaw cycles further enhances the system permeability. The study shows that the thermally induced effects on the system integrity of the BHE are larger and more significant than the subsequent frost-induced effects. The hydrophobic character of the high-density polyethylene (PE-HD) pipes as well as its high coefficient of thermal expansion seem to be the main points of weakness in the system. Optimization research should focus on the interface connection between grout and pipe, whereby hydrophilic pipe materials such as stainless steel or aluminum should also be considered as well as manipulation of the pipe surface properties of PE-HD.

İklim değişikliği ve çevre kirliliği günümüzde insanlığın karşılaştığı en önemli sorunlar arasında yer almaktadır. Enerji sistemlerinde kullanılan soğutucu akışkanların seçimi ve çevre dostu soğutucu akışkanların kullanımının önemi gün geçtikçe artmaktadır. Düşük küresel ısınma potansiyeline (KIP) ve ozon delme potansiyeline (ODP) sahip soğutucu akışkan seçimi çevre duyarlılığı açısından araştırmacılara önemli bir misyon yüklemektedir.Bu çalışmada, hidrokarbon soğutucu akışkan propan (R290) kullanılarak tasarlanmış bir ısı pompası sisteminin verimlilik analizi gerçekleştirilmiştir. Geleneksel ısı pompalarından farklı olarak tasarlanan bu sistemde; ısı geri kazanımı yapılarak, hem gerektiğinde kompresör çıkışındaki yüksek sıcaklıktaki soğutkanın hem de kondenser çıkışındaki soğutucu akışkanın ısısının depolanması ile bu durumlardaki verimlilik analizleri yapılmıştır. Yapılan analizlerde, ısı pompasının performans katsayısı (COP) değeri 2,75 olarak hesaplanmıştır. Geliştirilen modelde, defrost sürecince harcanan enerji miktarı elektrikli ısıtıcılı defrost yöntemine göre %63,6 oranında azaltılmıştır. Sistemin güneş enerjisinden de yararlanılarak daha da veriminin artırılabileceği öngörülmüştür., Climate change and environmental pollution are among the most important issues facing humanity nowadays. The importance of the selection of refrigerants used in energy systems and the use of eco-friendly refrigerants are increasing day by day. The selection of refrigerants with low global warming potential (GWP) and ozone depletion potential (ODP) imposes an important mission on researchers in terms of environmental awareness.In this study, efficiency analysis of a heat pump system designed by using hydrocarbon refrigerant propane (R290) was carried out. In this system, which is designed differently from traditional heat pumps; heat is recovered and efficiency analyzes are made for the case in which heat of the high temperature refrigerant at the compressor outlet is stored and for the case in which heat of the refrigerant at the condenser outlet is stored, when necessary. In the analyzes made, the coefficient of performance (COP) value of the heat pump was calculated as 2.75. In the developed model, the amount of energy consumed during the defrost process has been reduced by 63.6% as compared to the electric heater defrost method. It has been assessed that the efficiency of system can be even more by utilizing solar energy.

The aluminum alloy scroll is one of the key parts of the scroll compressors widely used in the air-conditioning, refrigeration, and heat pump systems. In this work, the semi-solid squeeze casting (SSSC) process was used to fabricate the aluminum alloy scroll. The effects of process parameters including the pouring temperature, mold temperature, and squeezing velocity on the filling and solidification behaviors of the alloys were investigated through simulations based on the power law cut-off (PLCO) material model. Results show that there is a significant increase in the flow velocity of the slurry, and the area of the high-speed region enlarges with the increase of the pouring temperature. The homogeneity of the temperature and velocity fields in the slurry is improved with an increase in mold temperature. Both the filling time and its variation rate decrease with an increase in squeezing velocity. The maximum solidification time exhibits a linear variation with the increase in pouring temperature. The shrinkage area is decreased by increasing the mold temperature. The optimal process parameters of the SSSC process were obtained from simulation analysis, which are the pouring temperature of 595 °C, mold temperature of 350 °C, and squeezing velocity of 0.3 m·s-1. Moreover, the qualified scroll casting was fabricated using the SSSC process under the optimal process parameters.

Food processing studies are important for both efficient use of energy and to obtain quality products. Yoghurt is a dairy product which consumes widely. Yoghurt producing facilities consumes high energy and run at low efficiency due to their traditional production methods. In order to produce quality yoghurt, pasteurized milk should be kept at 42-45 oC for 3-5 hours depending on the yeast type, this process called as incubation. After the incubation process, produced yoghurt must be cooled down to 20 oC in two hours depending on the package size of yoghurt. In conventional yoghurt production facilities, required heating and cooling are applied independently and this approach causes high energy consumptions, waste heat and the inefficient use of energy. In this study, a combined system consisting of a heat pump and a heat storage unit which is capable of the simultaneously heating and/or cooling application independently of each other is designed to ensure higher energy performance and efficiency. Thus, the required energy for heat transfer from the evaporator and cooling after the incubation process was ensured from the stored ice and, independently of the weight of the product, 64/68 units of energy (depending of refrigerant) were gained for each 100 units of required heating energy.The coefficient of performance (COP) of the system using R410a and R134a for heating, cooling and dual operation modes were calculated as 2.83, 1.83, 4.66 and 3.16, 2.16, 5.31, respectively. Energy costs for heat pump and conventional natural gas-fuel-oil boilers were compared. High energy efficiency and low energy consumption have been provided with the presented design, and suggestions for use for production facilities are given.

Thermodynamic properties and glass transition temperature (Tg) of heat pump dried scallop adductors with (SA-C) and without (SA) sodium alginate coating pretreatment were investigated. Single sodium alginate film (SF) was also performed for comparison. The isotherms for SA, SA-C and SF followed type II characteristics. Water adsorption capacity of SA was decreased with coating pretreatment. The net isosteric heat of adsorption (qst) and differential entropy (Sd) were exponentially decreased with increasing moisture content (MC). Spreading pressure (φ) was increased with rising water activity (aw), but decreased with elevated temperature. Sodium alginate coating pretreatment decreased the qst, Sd and φ of SA. The enthalpy–entropy compensation theory can be employed for the adsorption behaviors of 3 samples. It was enthalpy-driven non-spontaneous for SA, and enthalpy-driven spontaneous for SA-C and SF, respectively. Based on the aw concept and glass transition theory, adsorption isotherm and Tg data were modeled and combined to establish state diagram. Compared with SA, the critical MC and aw were, respectively, increased 7.14% and 187.5% with coating pretreatment. Hydrocolloids coating is an innovative pretreatment in enhancing the storage stability of dried foods.

This paper presents the analysis, simulation and performance study of heat transfer in a single U-tube borehole heat exchanger (BHE). Unsteady heat transfer method was used to analyze the heat transfer process of both inside and outside the borehole. Implicit numerical method applied on heat transfer equations obtained from energy balance (accompanied with thermal resistance model) was used to obtain the solution. The variation of mean fluid temperature, average borehole wall, grout and nearby ground temperature as well as borehole loading with borehole depth and time were investigated. Dynamic simulation was also performed to assess the influence of important parameters. The effect of two parameters, fluid mass flowrate and thermal conductivity of grout, on mean fluid temperature, borehole wall, grout and ground temperature as well as on borehole loading and borehole thermal effectiveness were investigated. The outcome of this study can substantially reduce the time devoted for research and to quickly determine the impact of various parameters on performance of vertical single U-tube borehole heat exchanger. Furthermore, the obtained result can be utilized as a reference for the design and optimization of heating and cooling system integrated with ground coupled heat pump system.

Σκοπός της παρούσας διατριβής αποτελεί η θερμική αποθήκευση με Υλικά Αλλαγής Φάσης (ΥΑΦ) μέσω ενσωμάτωσης α) στο κέλυφος του κτιρίου β) σε πρόσθετα ΦΒ του κτιρίου και μελέτης γ) της δυνατότητας απαγωγής της συσσωρευμένης θερμότητας των κυκλικών φορτίσεων των ΥΑΦ από αντλίες θερμότητας.Η διατριβή αναπτύσσεται σε δύο μέρη, το θεωρητικό και το πειραματικό. Στο θεωρητικό μέρος εξετάζονται οι τελευταίες εξελίξεις των ΥΑΦ στον κτιριακό τομέα. Το Κεφάλαιο 1 περιέχει την ανασκόπηση στις βασικές διαδικασίες που σχετίζονται με τα ΥΑΦ. Στο Κεφάλαιο 2, αναλύονται η ταξινόμηση και οι ιδιότητες των ΥΑΦ, ενώ απεικονίζονται οι τελευταίες εξελίξεις σε διάφορες τεχνικές αύξησης της μεταφοράς θερμότητας με πρόσθετα και άλλες νανοδομές. Το Κεφάλαιο 3 περιλαμβάνει την επανεξέταση των καινοτόμων εφαρμογών των συστημάτων Ηλιακής Θερμικής Αποθήκευσης με ΥΑΦ που έμμεσα ή άμεσα επηρεάζουν την κατανάλωση ενέργειας των αντλιών θερμότητας. Στο Κεφάλαιο 4 ακολουθεί η ανάλυση των δεδομένων των παραπάνω εφαρμογών. Το Κεφάλαιο 5 ολοκληρώνει το θεωρητικό μέρος της διατριβής με τα συμπεράσματα.Στο πειραματικό μέρος αναπτύσσονται τα πειράματα, η μεθοδολογία ανάλυσης και τα αποτελέσματα των πειραμάτων. Στο Κεφάλαιο 6 περιγράφεται η μαθηματική διαμόρφωση των μεταβατικών φαινομένων μεταφοράς. Αναλύονται η μέθοδος της αθροιστικής χωρητικότητας, η προσέγγιση Boussinesq και οι βασικές παραδοχές της επίλυσης του συστήματος των διαφορικών εξισώσεων ενέργειας, ορμής και συνέχειας που χρησιμοποιούνται αργότερα στα πειράματα. Γίνεται μια ανασκόπηση των λύσεων για τα προβλήματα των μεταβαλλόμενων οριακών συνθηκών και παρουσιάζεται το λογισμικό TRNSYS που χρησιμοποιήθηκε στα πειράματα για την μοντελοποίηση και επικύρωση των αποτελεσμάτων. Στο Κεφάλαιο 7 περιγράφονται τα πειράματα που εκτελέστηκαν στα πλαίσια της διατριβής. α) Αρχικά αναλύονται οι οριακές επιφάνειες γύρω και κάτω από το ΦΒ, οι περιβαλλοντικοί παράγοντες που επηρεάζουν τη θερμοκρασία του κυττάρου και η συσχέτιση με την εξεργειακή απόδοση του ΦΒ. Μετά τη μοντελοποίηση και την επικύρωση των μετρήσεων των πρόσθετων ΦΒ εξετάζεται η συμπεριφορά των καμπυλών I-V σε μεταβαλλόμενο φορτίο με και χωρίς ΥΑΦ. β) Η ενσωμάτωση των ΥΑΦ στο κέλυφος του κτιρίου προσομοιώνεται με το TRNSYS και βασίζεται στη βελτιστοποίηση της θερμοκρασίας τήξης του ΥΑΦ σε σχέση με την εσωτερική θερμοκρασία. Χρησιμοποιούνται τρία ΥΑΦ με αντίστοιχες θερμοκρασίες τήξης στους 20 ο C, 25 οC και 32 οC. Εξετάζεται η συμπεριφορά του ΥΑΦ σε διαφορετικές θερμοκρασίες έκθεσης του ρευστού μεταφοράς θερμότητας μέσω της ενσωμάτωσης στην εσωτερική και την εξωτερική επιφάνεια του τοίχου και αναλύονται οι διαφορές που παρατηρούνται. γ) Οι παραπάνω μετρητικές διατάξεις παρέχουν ενδείξεις για τους κύκλους φόρτισης και αποφόρτισης των ΥΑΦ και τις θερμοκρασιακές ροές κατά τη διάρκεια των πειραμάτων. Η απαγωγή της συσσωρευμένης θερμότητας από τις αντλίες θερμότητας μπορεί να βελτιώσει την συνολική απόδοση του συστήματος ΥΑΦ-ΠΦΒ-ΑΘ όταν γίνει με ελεγχόμενο τρόπο. Το Κεφάλαιο 8 συνοψίζει με συμπεράσματα τη διατριβή αυτή τα οποία συνιστούν και προτάσεις για περαιτέρω έρευνα.

The current work is focused on the Ground Source Heat Pump Systems (GSHPSs) coupled to closed vertical ground loop. Several factors that affect the system’s performance are examined. Two different approaches are developed. In the first one, an overall view of system’s performance is studied using GLD 2009, GLHEPRO 4.0a and TRNSYS 17. The system is examined as a total of unbreakably connected parts. A parametric analysis is performed to examine the influence of undisturbed ground temperature, Ground Heat Exchanger (GHE) length and borehole separation distance to system’s operational characteristics, so as to cover given building loads. In the second one, the operation of parts is examined independently of the system. The borehole thermal resistance is examined through different types of analysis such as analytical correlations, commercial software GLD 2009 and 2-D finite element analysis through COMSOL 4.0a. Despite the different type of analysis, the deviations are small and that is why borehole thermal resistance output values are considered satisfactory. In addition, MATLAB codes are built to simulate the operation of heat pump and open circuit cooling tower that may be included in a Hybrid Ground Source Heat Pump System (HGSHPS). By studying heat pump’s refrigeration cycle, alternative refrigerant mixtures to R-410A are proposed. Furthermore, the performance of cooling tower is evaluated with the ratio pressure drop per packing height for four packings. The results are generally applicable to the estimation of the performance of these devices and not restricted only to geothermal applications. Moreover, a HGSHPS coupled to a closed circuit cooling tower is studied. A new strategy is developed to control this system so as to minimize its electric power consumption. Despite the fact that it is designed considering only the net cooling period, it is a well-promising policy because it is based on the continuous monitoring of system’s previous hourly state, so as to adjust its operation to the following hour (feedback).%%%%Η παρούσα eργασία eπικeντρώνeται στα συστήματα αβαθούς γeωθeρμίας που έχουν κατακόρυφο κλeιστό κύκλωμα γeωeναλλακτών. Πολλοί παράγοντeς που eπηρeάζουν την απόδοση του συστήματος eξeτάζονται. Δύο διαφορeτικές προσeγγίσeις αναπτύσσονται. Μe την πρώτη, η απόδοση του συστήματος eξeτάζeται συνολικά χρησιμοποιώντας τα λογισμικά GLD 2009, GLHEPRO 4.0a και TRNSYS 17. Το σύστημα eξeτάζeται ως ένα σύνολο από αναπόσπαστα συνδeδeμένα τμήματα. Μια παραμeτρική ανάλυση eκτeλeίται για να μeλeτηθeί η eπίδραση της αδιατάρακτης θeρμοκρασίας του eδάφους, του μήκους του γeωeναλλάκτη και της απόστασης των γeωτρήσeων στα λeιτουργικά χαρακτηριστικά του συστήματος έτσι ώστe να καλυφθούν τα δeδομένα φορτία του κτηρίου. Μe τη δeύτeρη, η λeιτουργία των τμημάτων του συστήματος eξeτάζeται ανeξάρτητα. Η θeρμική αντίσταση της γeώτρησης μeλeτάται μe διαφορeτικά eίδη ανάλυσης όπως μe αναλυτικές σχέσeις, μe το eμπορικό λογισμικό GLD 2009 και μe μια δισδιάστατη ανάλυση πeπeρασμένων στοιχeίων μέσω του COMSOL 4.0a. Παρά τα διαφορeτικά…

The paper attempts to analyze the technical possibilities of using a compressor heat pump to recover waste heat from energy processes implemented by a watercraft. The amount of waste heat that could be used for the heating needs of the vessel was estimated and the hydrothermal potential of the marine waters was assessed. The possibilities of reducing the power of the ship's power plant used to power the ship's heating installation were determined.

This article discusses the mathematical models of the individual structures and modes of operation of a double-circuit solar collector with thermo siphon circulation. To perform this task, we considered a new design of a flat solar collector with thermo siphon circulation, in which the heat transfer coefficient was increased by eliminating additional partitions between the panel and thermal insulation. The efficiency of the solar collector is achieved due to the presence of the metering tank and the heat pump in the tank, where the condenser and evaporator are made in the form of a “spiral in a spiral” type heat exchanger, and the heat exchanger pipelines are placed one above the other, which allows increasing the area and intensity of heat exchange. The result of this work is a theoretical and mathematical analysis of the unsteady thermal regime of flat solar collectors on the modes of operation under consideration. Based on the results of the analysis, it is possible to optimize individual structural elements, as well as to predict the thermal regime and select alternative solutions for the design of flat solar collectors and the choice of operating modes.

BACKGROUND Drying efficiency and quality maintenance are the major concerns of both manufactures and consumers. Heat pump drying (HPD) is suitable for heat sensitive foodstuffs due to its ability to independently control the drying operation parameters. However, lower drying rate and energy efficiency in the later period of HPD are the bottlenecks that restrain its application. A novel approach using hydrocolloids as pretreatment coatings prior to drying was designed to solve these problems. The effects of sodium alginate (SA) coating, drying temperatures and air velocities on the drying characteristics and quality attributes of scallop adductors were evaluated. RESULTS Drying took place in the falling rate period. Drying time decreased with increasing temperature, air velocity and SA coating. The Two Term model and the Wang and Singh model gained the best fit for thin-layer drying of scallop adductors and SA film, respectively. Effective moisture diffusivity increased with temperature, velocity and SA coating and were in the range 7.352-14.620 × 10-11 , 9.890-17.100 × 10-11 and 2.348-4.604 × 10-10 m2 s-1 for uncoated scallop adductors, SA coated scallop adductors and SA films, respectively. The activation energies for SA films, coated and uncoated scallop adductors were 17.07, 20.78 and 26.17 kJ mol-1 , respectively. Dried scallop adductors with SA coating pretreatment exhibited a significant lower value of shrinkage rate and hardness, and higher value of toughness than uncoated ones at 30 °C and 2.0 m s-1 (P

Borehole Heat Exchanger is one of the main elements of Ground-Coupled Heat Pump and its performance is directly related to the heat pump Coefficient of Performance. In this paper, a comprehensive numerical simulation model was built to evaluate the annual performance of the shallow Borehole Heat Exchanger installed in different soils subjected to land surface seasonal hydrothermal variations. It was found that the shallow Borehole Heat Exchanger installed in sand had a better performance of 8% than in clay. The same performance difference between sand and clay was observed in most of the investigated scenarios. The annual average heat pump performance presented a variation more than 27.2% with the meteorological condition, the grout thermal conductivity and the heat load level. The multi-pipe solution and the carrying fluid velocity also influenced the heat pump performance, ranging between 12.2 and 16.2%. Other factors such as the hydraulic condition, the groundwater flow, the grout volumetric heat capacity, the grout diameter, the shank spacing, the pipe inner diameter, the pipe thickness, the pipe thermal conductivity, the carrying fluid material and the heat load mode had less impact on the heat pump Coefficient of Performance, varying between 0 and 11.6%. These findings could be used as a guideline for the future studies of Borehole Heat Exchanger, especially for the applications installed in unsaturated soils.

Purpose.The paper analyses the possibility and terms of increasing the efficiency of heating and ventilation systems of public buildings at the present stage of development and the specific climatic conditions of Ukraine. The main purpose is to develop specific measures for public buildings, which will lead to a significant reduction in energy costs for heating and air conditioning system. The example is similar system of DNURT compact campus, which is heated with its own autonomous boiler that uses natural gas.Methodology. The statistical heat loss analysis for the last 5 years allows defining the types and calculating the heat loss values for specific conditions. These losses are compared with those in the world practice and based on the comparison and analysis of the current system there are offered the ways to reduce the heat loss values through the use of various technical and organizational methods.The paper also proposes involvement for this purpose of secondary and alternative energy sources. The secondary energy resources include the heat that is emitted by people and that coming out with the air during ventilation of buildings. The renewable sources include solar and geothermal energy. To enhance the heat transfer medium temperature capacity it is proposed to use the heat pumps.Findings. The maximum possible use of the proposed measures and implementation of rational schematic and engineering solutions for heat and hot water supply systems cam reduce the energy loss for heating and hot water by 30-35%.Originality. The paper for the first time proposed the use of new integrated approaches to maintain the desired heat balance in the winter period, as well as the new schematic solutions for heating and ventilation systems, both in winter and in summer, based on the use of heat pumps and secondary energy resources.Practical value. The introduction of the proposed schematic solutions and approaches demand relatively small capital investments and do not require significant reconstruction of already installed systems.

This paper presents a comprehensive review on developments and advances of Solar Assisted Heat Pump technology reported in 21st century. Combination of thermal and photovoltaic solar collectors with heat pumps has been widely used in recent decades for simultaneous heat, hot water and power generation for a broad range of applications, from providing domestic and commercial buildings with heat and power to manufacturing and agricultural applications. This review critically analyses the research reported in past two decades with particular attention to the works with substantial importance for future development of the technology. Four distinctive investigation periods were considered and key developments and dominant technologies at each period were reported. The main novelties and breakthroughs in solar assisted heat pump technology, as identified by this review, are: (1) The ban on R-12 refrigerant which lead to dominance of R-134A refrigerant for a wide range of systems and applications, (2) Increasing interest in Solar-assisted Ground Source Heat Pumps following the technological advances that made the utilization of such systems cost effective, (3) Advances in numerical analysis methods and use of Artificial Intelligence applications in investigating performance and effectiveness of various systems, and (4) Integrating the Photovoltaic/Thermal collectors with heat pumps for simultaneous heat and power generation resulting in improved performance and reliable operation of systems under severe operating conditions.

A ground source heat pump system is a highly efficient renewable heating, cooling, and ventilation system that utilizes the ground as a heat source or sink via ground heat exchangers. Energy pile is an energy geotechnical structure that couples a ground heat exchanger with a geotechnical structure, leading to low capital cost. The design of energy piles can be challengeable due to their complicated geometries and the requirement of mechanical load. This study focuses on the heat transfer across the concrete&ndash, soil interface of energy piles in urban areas. Case studies from two projects, the Lambeth College and Shell Centre projects, are presented and discussed. The back analysis of two energy pile cases illustrated that the heat transfer coefficient at the pile&ndash, soil interface can differ between the cooling mode and the heating mode. It can be concluded that the difference in the heat transfer coefficient is influenced by a number of factors such as soil properties, concrete (grout) properties, and the installation method.

In this paper, a new adsorbent composite coating by using SAPO-34 filler in a sulfonate polyether ether ketone matrix is proposed for thermally efficient adsorption heat pumps. Composite SAPO-34 zeolite based coatings with 80–95 wt% SAPO-34 content were realized. Preliminary morphological analysis, by scanning electron microscopy, highlighted that the coating microstructure is homogeneous and permeable to water vapor diffusion. Water vapor adsorption isobars were measured at equilibrium for all samples in the temperature range 30–120 °C. The results showed the typical S-shaped trend, which is suitable for adsorption heat pump applications. The highest adsorption value was observed for the coating with highest zeolite filler amount, 95 wt%. This batch exhibited a maximum water uptake of about 29.0 wt%, demonstrating that the S-PEEK matrix does not hinder the SAPO-34 adsorption performance. Finally, starting from obtained experimental data of composite materials adsorption capacities the, a simple energy balance based thermodynamic analysis was performed for air conditioning application by using an aluminum finned-flat tube heat exchanger, as reference. Results highlight that this composite coating technology allows cooling COP up to over 5% higher than that of the conventional loose adsorbent grains configuration, indicating the proposed technology promising for practical application in adsorption heat pumps.

This research study investigates the effects of the large-scale installation of domestic heat pumps on the UK electricity supply over the short to medium term. A BREDEM-based dwelling energy model, incorporating a model of heat pump performance, is enhanced for the effects of varying monthly temperatures. Data from the English Housing Survey (2007) are analysed using this model to estimate electricity consumption to 2020 and 2050, and simulate scenarios for replacing existing heating systems by ground or air source heat pumps. The type of heat pump (ground or air source) is determined by dwelling plot dimensions data from the EHS. Modelling results for 2020 showed that a policy of replacing the heating systems with the highest emissions could reduce or at least minimise the increase in electricity consumption and carbon emissions. Results for 2050 showed that replacement of some 80% of current gas-fired systems would enable the UK to meet its target of 80% carbon emissions reduction in this sector when accompanied by simultaneous decarbonisation of the electricity supply. These results provide some support for the UK government's policy of subsidizing heat pump installations through the Renewable Heat Incentive payments while indicating that meeting emission targets requires far greater adoption of these systems than current ambitions.

The new standards on energy saving for new and existing buildings have animated both researchers and technicians in recent years, aiming at reducing the dependence on fossil fuels, improving indoor comfort, and systems efficiency. In this scenario, special attention must be paid to historical buildings that need to preserve their key testimonial heritage within the society. This paper describes the design and realization stages of a pilot system based on a ground-coupled heat pump, operating both in heating and cooling modes, installed in the monumental site of Saints Marcellino and Festo (SM&F), in Naples, Southern Italy. This study aims to demonstrate that low-enthalpy geothermal systems can be employed as energy retrofit applications in buildings of historical, artistic, and cultural interest and, at the same time, to prove that the use of this technology allows achieving the objectives, set at global level by the current regulations, and requiring a reduction of carbon dioxide emissions (tCO2) of 53% compared to technology using fossil fuels.

The highest challenge of energy efficiency of building stock is achieving improved performance in existing buildings and, especially, in heritage buildings which per se are characterized by massive limitations against the implementation of the most sophisticated solutions for energy saving. In Italy, historical buildings represent more than 30% of the building stock and the vast majority require energy retrofit, while ensuring the preservation of the heritage value and acceptable comfort conditions. In this context, historical buildings must be retrofitted and re-functioned by introducing innovative technologies aimed at reducing energy consumption and improving human comfort, health, and safety. To this aim, this study implements the Historic Building Information Modeling (HBIM) approach for the integrated modeling, monitoring, management, and maintenance of a novel geothermal system involving horizontal ground source heat exchangers (GHEXs) coupled to an adsorption heat pump for the energy refurbishment of historical buildings. In detail, a rural building part of a medieval complex in Perugia, Central Italy, is considered as a pilot case study. The analysis stresses the potential of the Facility Management (FM) applications of HBIM to provide a tool for the human-centric operational management control of the building energy performance and indoor comfort when combined with the building monitoring and supervision system. Therefore, this integrated HBIM approach may drive the path towards the user-centric re-functioning of heritage buildings.

Keeping product temperatures homogeneous is an important problem in defrosted industrial coolers. In this study, it is aimed to obtain findings that will shed light on researchers and producers by analyzing the defrosting process of the industrial cooler. For these reasons, the system was designed using R290 (propane), a new generation refrigerant with a single evaporator, double condenser and double compressor, in order to ensure homogeneous cooling. By keeping the cooled products in the range of – 1 ℃ and +5 ℃ as required by the standard, during the experiment, temperature-pressure measurements of the refrigerated products and cooling system equipment were taken from certain points every minute and test data were recorded. The average temperature and relative humidity values measured minute of the environment where the experimental setup is located was calculated as 25℃ ±1℃ and 60%±0.02%, respectively. During the experiment, eight defrost operations were performed, and it was observed that the average temperature values taken from the products during the 24 hours during defrosting changed to 3.07℃. During the experiment, the highest and lowest temperatures of the cooled products were measured as 4.22℃ and 2.02℃. Increased product temperatures and cooling stopped during defrosting increased the power consumption in the system. In order to observe the effect of the power consumption on system performance, COP values after each defrost time were calculated as 2.31, 2.30, 2.29, 2.60, 3.36, 3.29, 3.30, 3.49, respectively. When the defrost process of cooling system analyzed, it was seen that the products were successfully cooled at desired temperature ranges in the scope of TS EN ISO 23953-2.

Zeolite faujasite (FAU) is widely used as a catalyst and adsorbent in many industrial catalytic and separation applications. The high water adsorption capacity of zeolite FAU makes it an attractive adsorbent material for the heat pump and heat storage applications. However, highly alkaline condition, which is required for the synthesis of zeolite FAU, is a challenge to achieve FAU/aluminum composites via a direct, reactive coating approach. In this contribution, a reactive coating method to fabricate zeolite FAU based aluminum composites is presented. The impact of important synthesis paramaters on the formation of such composites is discussed based on thorough characterization (such as XRD, SEM, MAS NMR, N2- and water-sorption) of the coated FAU layer (the composite) and so-called excess powder, formed parallel in the reaction solution. Along with the comprehensive study of zeolite FAU formation as a coating layer, preliminary results of the fabricated composites in potential heat pump application are presented as well.

Ground thermal properties, including the thermal conductivity and diffusivity of both soil and grout, are significant considerations for the design of a ground-coupled heat pump (GCHP) system. However, as a result of the limitations inherent in available response models, few in-situ thermal response tests (TRTs) can identify grout thermal conductivity and diffusivity. This paper proposes a new method to estimate the thermal conductivity and diffusivity of both soil and grout simultaneously using the recently developed infinite composite-medium line source (ICMLS) model. Firstly, a linear dependence analysis is performed on the aforementioned four parameters to ensure the feasibility of the proposed method, leading to an estimation of the minimum TRT duration. Secondly, uncertainty analysis is carried out to analyze the influence of U-pipe shank spacing, as it is considered a sensitive parameter in modeling the heat transfer of ground heat exchangers (GHEs). Thirdly, a genetic algorithm is used to identify these four parameters using the data collected from a TRT. The proposed method is verified using a well-designed sandbox experiment. Finally, its application is demonstrated and evaluated by applying it to the design of a GCHP system for an office building at Hunan University.

Iron tailings are the remains of solid waste after iron ore concentrates are selected by mineral processing technology. For a long time, iron tailings are disposed through accumulation and burial, which not only occupy large space but also increase the cost of treatment. Ground source heat pump (GSHP) system is a kind of environmental-friendly, energy-saving system by using geothermal energy. This is getting more and more wide use in China. The main problem of using GSHP is the low thermal property of backfill materials in the loess region of Northwest China, which affects the thermal efficiency of GSHP system. Improving the thermal conductivity of backfill materials is necessary and urgent for energy conservation. The authors hypothesized that thermal efficiency increases as the rate of tailings addition increases. To test this hypothesis, the authors applied iron tailings to the backfill material. Experiments were conducted to measure the thermal conductivity of the loess and iron tailings, determined under the conditions of different dry density, water content, and mixing ratio. Then, the changes of thermal conductivity were analyzed as tailings' mix proportion varies. The optimum mix ratio was determined and the reason was discussed. The results showed that the thermal conductivity of backfill material is a formula of saturation and rate of tailings addition. A series of functional equation was given in the end. The calculated value of the formulae matched well with the experimental data. The research concluded that the iron tailings as backfill material of GSHP is feasible and the result can be used as a reference for related engineering research.

Water reuse and desalination systems are energy intensive processes, and their increasing use is leading energy consumption within water systems to be an increasingly important issue. Shower wastewater contains large amounts of heat, so there is an opportunity to recover energy from shower water to offset energy consumption elsewhere in water systems. This paper found ways to increase the output of hot water and lower the energy consumption by establishing a thermodynamic model of an instantaneous wastewater source heat pump. The system proved to be very effective, the heating COP (coefficient of performance) can reach 3.3 even in the winter. Under the conditions of limited heat transfer area, reducing the suction pressure of a compressor is a more feasible way to increase the hot water output to meet the needs of users rather than increasing the discharge pressure. Besides, increasing the heat transfer area of the evaporator is a more effective option. When the heat transfer area of evaporator varies from 0.5 to 1.0 square meters, a notable change is that the heating COP increases from 3.283 to 3.936. The heating COP in a system with a recuperator can reach 5.672, almost double that compared to the original systems.

At present, specialists of foreign and domestic research organizations and industrial firms pay much attention to the use of steam compression heat pump plants (HPP) as an energy-saving technology. Modern compressor units allow receiving 3-4 kW for 1 kW of power consumed by HPP, and under certain conditions up to 5-6 kW of useful power. Today HPPs are most used in heat supply systems for residential and office buildings, especially in Scandinavia, Germany, Switzerland, USA, Japan, China. The paper discusses features of the operation of steam compressor heat pump plants as systems for improving energy efficiency with a description of the device of a heat pump plant; its main components are also listed. Review of the existing practice of introducing such systems in foreign countries is presented, including in Minsk - the Minsk metro, and in Russia - the Moscow Metro. The project, performed by specialists of JSC “VNIIZhT” and MIIT, is considered for the Moscow Metro (with reference to the heating systems of the Nagatinskaya and Pushkinskaya metro stations) for the use of dumping heat of ventilation shafts for heating and hot water supply, proposed by scientists of JSC “VNIIZhT” in 2012 within the framework of the exhibition of technical achievements. Authors presented information on the implementation of the pilot project at the station “Salar’yevo” (Moscow Metro) on the use of HPP in the heat and cooling supply system of the station for further comprehensive analysis of the effectiveness of the HPP application in the operating conditions of the metro. From the analysis of the data given in the work, it is concluded that metro systems are significant sources of low-potential heat, which can be used for the heat supply of stations and/or nearby urban sites by means of HPP. By now, there is a lot of experience (especially abroad) of the practical application of HPP in the heat supply systems of facilities. Nevertheless, for a reliable and comprehensive assessment of the feasibility and cost-effectiveness of projects using low-potential heat of metro systems as an energy-saving technology, a complex of studies is needed, including operational tests of currently implemented pilot projects.

This work investigates the effects of different operation modes on the restoration performance and operation characteristics of a ground source heat pump (GSHP) system backfilled with phase change materials (PCM). A numerical GSHP system model considering site conditions and dynamic loads was developed and validated. The effects of daily working schedules, load features and operation schedules of short time period operation modes, and phase-transition temperature of PCM grout were explored. The results show that PCM grout is more suitable for buildings with less-persistent thermal demand considering the importance of restorability. Operating the GSHP with cooling & heating alternate load is the most effective way to improve the overall performance of the system, but a suitable operation schedule should be used. Decreasing the cycle ratio is the best method to promote the system performance under the same hourly load intensity, while for the operation schedules with higher hourly load intensity, a shorter cycle period is recommended. The phase-transition temperature of PCM grout influences the system stability and sustainability greatly as it controls when the melting occurs. The grout with the phase-transition temperature of 20.4 °C is demonstrated to be the most suitable one under our conditions as it provides relatively stable and effective performance over the entire summer and has a higher utilization ratio of the latent heat.

This paper discusses about the possibility of using a heat pump when compressing hydrogen with metal hydride materials. Hydrogen is absorbed into the alloy at low pressure and temperature. Increasing the temperature of the alloy by absorbed hydrogen results in a significant increase in pressure, with hydrogen desorption being carried out at an increased equilibrium pressure. A compressor working with MH materials requires cyclic heating of the reservoir from which hydrogen will be desorbed and absorbed.

© 2018 Elsevier B.V. As one of the latest emerging HVAC technologies, the Variable Refrigerant Flow (VRF) system with heat recovery (HR) configurations has obtained extensive attention from both the academia and industry. Compared with the conventional VRF systems with heat pump (HP) configurations, VRF-HR is capable of recovering heat from cooling zones to heating zones and providing simultaneous cooling and heating operations. This can further lead to substantial energy saving potential and more flexible zonal control. In this paper, a novel model is developed to simulate the energy performance of VRF-HR systems. It adheres to a more physics-based development with the ability to simulate the refrigerant loop performance and consider the dynamics of more operational parameters, which is essential for representing more advanced control logics. Another key feature of the model is the introduction of component-level curves for indoor units and outdoor units instead of overall performance curves for the entire system, and thus it requires much fewer user-specified performance curves as model inputs. The validation study shows good agreements between the simulated energy use from the new VRF-HR model and the laboratory measurement data across all operational modes at sub-hourly time steps. The model has been adopted in the official release of the EnergyPlus simulation program since Version 8.6, which enables more accurate and robust assessments of VRF-HR systems to support their applications in energy retrofit of existing buildings or design of zero-net-energy buildings.

Bu çalışmada solartermal sistemlerin ısı pompası ile kombinasyonu sayısal olarak incelenmiştir.Kollektörlerin potansiyel faydası ısı pompası sistemleri kombine sistemlerlekarşılaştırılarak bulunmuştur. Muğla ili için tüm simülasyonlar POLYSUNprogramı kullanılarak yapılmıştır. Simülasyonu yapılan sistemler tek hanelikonutların kullanım sıcak suyu ve konut ısıtması ihtiyacını karşılayacakşekilde tasarlanmıştır. Bu çalışmanın sonuçları sistemin mevsimsel performansfaktörünün hava kaynaklı ısı pompası sistemine eklenen kollektör alanı arttıkçaarttığını göstermektedir. Ancak ısı talebinin karşılandığı sistemlerde ısıpompasının ısıtma tesir katsayısının azaldığı sonucuna ulaşılmıştır. Busistemde solar enerji sıcak su ihtiyacını karşılamak için kullanılırken birtaraftan da konut ısıtılmasına destek olmaktadır. Ancak yetersiz kapasitede ısıpompası seçilerek kollektör sayısının arttırılmasının talebi karşılamadığı bunedenle yeterli kapasitede ısı pompası seçilmesi gerektiği saptanmıştır. Isıtalebinin karşılanamadığı sistemlerde ise 2 kollektörden sonra ısıtma tesirkatsayısının sabit kaldığı görülmüştür. 2 kollektörden fazla sayıda kullanılankollektörler yazın ihtiyaç fazlalığından kapatılmaktadır. Ancak kış dönemindeısıtmaya destek olmaktadır., In this study, thecombination of solar thermal systems with heat pump has been investigatednumerically. The potential utility of the collectors is found by comparing heatpump systems with combined systems. All simulations for the Muğla province weremade using the POLYSUN program. The simulated systems are designed to meet thedemand for hot water and residential heating of single-dwelling houses. Theresults of this study show that the seasonal performance factor of the systemincreases as the collector field added to the air source heat pump systemincreases. However, in the systems where the heat demand is met, the heatingeffect coefficient of the heat pump (COPHP) decreases. In this system, solarenergy is used to meet the need for hot water, while also supporting housingheating. However, it has been determined that the heat pump should be selectedat a sufficient capacity because the increase in the number of collectors byselecting the heat pump at the insufficient capacity cannot meet the demand.However, it has been determined that the heat pump should be selected at asufficient capacity because the increase in the number of collectors byselecting the heat pump at the insufficient capacity cannot meet the demand. Inthe systems where the heat demand cannot be met, the heating effect coefficientafter 2 collectors is found to be constant. Collectors used in excess of 2collectors are closed when there is no need for them. However, it supportsheating in winter.

Electric clothes dryers consume about 6% of US residential electricity consumption. Using a solid-state technology without refrigerant, thermoelectric (TE) heat pump dryers have the potential to be more efficient than units based on electric resistance and less expensive than units based on vapor compression. This paper presents a steady state TE dryer model, and validates the model against results from an experimental prototype. The system model is composed of a TE heat pump element model coupled with a psychrometric dryer sub-model. Experimental results had energy factors (EFs) of up to 2.95 kg of dry cloth per kWh (6.51 lbc/kWh), with a dry time of 159 min. A faster dry time of 96 min was also achieved at an EF of 2.54 kgc/kWh (5.60 lbc/kWh). The model was able to replicate the experimental results within 5% of EF and 5% of dry time values. The results are used to identify important parameters that affect dryer performance, such as relative humidity of air leaving the drum.

Finland is one of the northernmost countries utilizing ground source heat pumps (GSHPs). In this north European country, GSHPs’ operating conditions are characterized by the cold climate, and hard, crystalline bedrock. Environmental risks and technical problems with ground heat exchangers (GHEs) have been much discussed, but the frequency of complications has not been previously studied in Finland. This article examines the types and construction practices of GHEs, and the range of problems in GHEs experienced by the practitioners. The data was collected through a questionnaire study among Finnish GSHP practitioners, and thematic interviews of Finnish heat pump experts. Borehole heat exchangers (BHEs) proved to be the most popular GHE type in Finland with a share of 85%. The questionnaire responses indicate that the most common complications in BHEs are connected to collapsed boreholes, and artesian or otherwise abundant water yields. Also, issues relating to heat transfer fluids, drilling through multiple aquifers, and design errors are discussed.

The second part of this review presents a comprehensive review on applications of solar assisted compression heat pump systems and its associated research potentials. The reported investigations on solar assisted heat pumps are categorized into five major groups as follows: (a) drying, (b) room space heating; (c) agricultural green house space heating, (d) water heating and (e) desalination applications. Most of the reported investigations in open literature are reviewed. The study will then presents the major limitations of solar assisted compression heat pumps and further research tasks in various applications. This paper concludes that solar assisted compression heat pump system is the promising equipment used for heating applications. The information presented in the second part of the review is beneficial to the researchers, energy experts and decision makers in the field.

Negative effects of fossil fuels and the fact that their reserves will be exhausted in the near future have made nations all around the world look for novel replacing technologies. In recent years, the Ground Source Heat Pump (GSHP) has been considered as one of those beneficial solutions in industrial countries. It is obvious that for a replacing technology to be economically favourable is as important as being technically feasible. Iran is a country of several climates and needs to expand its energy basket for development. In this paper, the impact of temperature and humidity variations on the economics of a GSHP system is studied. In order to find the best region to install GSHPs, 9 different areas are selected with respect to ambient temperature and humidity diversity. Then, feasibility studies are carried out using RETScreen software to estimate the profitability of the project. The result indicates that the impact of a humidity variation is negligible in comparison with the temperature variation. Also, to determine the importance of the Iranian government’s incentive on the feasibility of GSHP projects, the natural gas price trend is considered in two scenarios. Further, a predicting equation to calculate annual cost based on temperature and a relative cooling/heating load is conducted by a regression method. Finally, the reduction in CO 2 emissions due to the possible utilization of a GSHP system is determined in each region.

This paper presents a comprehensive review on research and developments on solar assisted compression heat pump systems, mostly reported during the last two decades. The first part of this paper provides a detailed description of the past efforts on various system configurations, system modeling, enhancement of system performance, modifications in compression heat pump cycles and environment friendly refrigerant options for solar assisted compression heat pump systems. The economical and environmental impacts of solar assisted compression heat pump systems are also described. Further research needs in this important field of solar assisted compression heat pump are listed. The outcomes of this review confirm that, there is a lot of research scope for improving the performance of the system and reducing its initial cost to make it competitive in the global market. The information presented in this paper is shall be highly beneficial for the active researchers working presently on solar assisted compression heat pumps.

The use of artificial neural networks (ANNs) in various applications has grown significantly over the years. This paper compares an ANN based approach with a conventional on-off control applied to the operation of a ground source heat pump/photovoltaic thermal system serving a single house located in Ottawa (Canada) for heating and cooling purposes. The hybrid renewable microgeneration system was investigated using the dynamic simulation software TRNSYS. A controller for predicting the future room temperature was developed in the MATLAB environment and six ANN control logics were analyzed.The comparison was performed in terms of ability to maintain the desired indoor comfort levels, primary energy consumption, operating costs and carbon dioxide equivalent emissions during a week of the heating period and a week of the cooling period. The results showed that the ANN approach is potentially able to alleviate the intensity of thermal discomfort associated with overheating/overcooling phenomena, but it could cause an increase in unmet comfort hours. The analysis also highlighted that the ANNs based strategies could reduce the primary energy consumption (up to around 36%), the operating costs (up to around 81%) as well as the carbon dioxide equivalent emissions (up to around 36%). Keywords: Hybrid microgeneration system, Ground source heat pump, Photovoltaic thermal, Artificial neural network, Predictive control, Energy saving

In this study the potential for data center waste heat utilization was analyzed in the Nordic countries. An overview of upcoming data center projects where waste heat is utilized is presented. Especially in Finland data center operators are planning to reuse waste heat in district heating. However, business models between the district heating network operator and data center operator are often not transparent. The implications of economics and emissions on waste heat utilization in district heating were analyzed through life cycle assessment. Currently the biggest barriers for utilizing waste heat are the low quality of waste heat (e.g. low temperature or unstable source of heat) and high investment costs. A systematic 8-step change process was suggested to ensure success in changing the priority of waste heat utilization in the data center and district heating market. Relevant energy efficiency metrics were introduced to support rational decision-making in the reuse of waste heat. Economic calculations showed that the investment payback time is under the estimated lifetime of the heat pump equipment, when waste heat was utilized in district heating. However, the environmental impact of waste heat utilization depends on the fuel, which waste heat replaces.

This study conducts a techno-economic analysis to seek the feasibility to integrate a zero-emission building (ZEB) with a commercial-scale hydrogen vehicle (HV). The parametric analysis is conducted in 16 simulation groups with respect to the equipment options of the solar thermal collectors, the ground source heat pump (GSHP) and the HV refueling methods, while each group contains a series of cases with a range of on-site renewable electricity (REe) generation capacities between 0 and 16 kW. The assessment criteria include the annual operational equivalent CO2 emission and the relative net present value (NPVrel). By the parametric analysis, the sets of the non-dominated cases within the cloud of the analysed solutions have been comprehensively investigated regarding the aims to reduce the emission and the cost. With respect to the criteria of the equivalent emission and NPVrel under the normal market scenario of the electrolyzer (5000 EUR/kW), none of the cases with the on-site H2 system can be identified as superior to those without the on-site H2 system. The non-dominated cases will mainly happen to those with a 0–9.61 NOCT kW photovoltaic (PV) panel and a 5 kW GSHP but without any solar thermal collector, which have a range of NPVrel between −4115 and 12,556 EUR along with a range of emission between 19.72 and 6.65 kg CO2,eq/m2 a. However, by reducing the electrolyzer cost to the lowest market scenario of 2000 EUR/kW, parts of the cases with the on-site H2 system start to challenge those without the on-site H2 system. Moreover, the change of the emission factor of the H2 fuel from 0.267 to 0.141 kg CO2,eq/kWhLHV will not alter the set of the overall non-dominated cases, but will uniformly reduce the annual emission of these cases by a magnitude of 3.83 kg CO2,eq/m2 a.

Among the thermal error sources of the high accuracy and efficiency machine tools, the thermal errors induced by the heat generated from running high speed motorized spindle is the crucial one. A new thermal error control method for motorized spindle is suggested, which is based on the thermal deformation balance principle. The essential idea of the method is to utilize the thermal contraction of Carbon Fiber Reinforced Plastic (CFRP) to restrain the thermal elongation of metal spindle housing. In the designed control system, the CFRP bars are uniformly distributed around the spindle housing, and the ThermoElectric Modules (TEMs) works as the heat pump which transfers the heat from spindle housing to CFRP bar. The experimental and numerical simulation results show that the suggested approach reduces 97% thermal displacement compared with the motorized spindle without the suggested thermal error control system. It is expected that the suggested method can also be applied to thermal error control for various cylindrical high-precision parts including aerospace equipment, optics and optical instruments.

To cope with tunnel frost damage, studies on prevention methods are routinely conducted to improve environmental protection and energy saving. Based on field investigations, the main available thermal insulation methods and their application are discussed and analysed in this paper. The results show that passive measures, such as a thermal insulation layer or door, cannot completely avoid frost damage. Construction investment of the electric heat tracing (EHT) system is lower at the early stage, but a large investment in operation and pollution problems are needed in the later period. As renewable, clean and environmentally friendly primary energy, geothermal energy can realize energy-saving and emission-reduction. Furthermore, our research team proposed the optimization design method for tunnel heat insulation and anti-freezing by using geothermal energy and presented the challenges for future applications of the ground-source heat pump (GSHP) system in tunnels. The results regarding energy conservation from this review can provide useful technical support in design, operation and management of tunnels in cold regions.

To study the effects of using phase change materials (PCMs) as grout on the efficiency of a ground source heat pump (GSHP) system, a numerical GSHP system model was established in this study, considering both the site conditions and dynamically changing loads regulated by the heat pump. First, system efficiencies of using an ordinary grout and two other PCM grouts were investigated and compared. Second, the applicability of PCM grouts to different soil environments was investigated by analyzing the effects of subsurface characteristics on the heat exchanger efficiency. Finally, the appropriate operation mode for PCM-backfilled GSHP system was determined by comparing the effects of daily running modes with various intermittent ratios on the system performance. The results show that it is necessary to consider the effect of heat pump, especially for poor heat transfer conditions. PCM grouts with a low thermal conductivity will significantly reduce the system efficiency, whereas PCM grouts with a thermal conductivity comparable to that of an ordinary grout will improve the efficiency and operational stability of a GSHP system. A higher soil thermal conductivity and Darcy velocity improve the heat exchanger efficiency, and PCM grouts with a high thermal conductivity are more suitable for areas where the groundwater is not rich. Sufficient recovery time is necessary and important for a PCM-backfilled GSHP system to ensure operational stability and sustainability and the effectiveness of thermal radius reduction.

This paper investigates the use of a vertical coaxial borehole heat exchanger (BHE), focusing on those consisting of standard geothermal piping material, as a component in a ground-source heat pump system. The results of a lab-scale experiment are used to verify the trends exhibited by a recent semi-analytical model, referred to as the composite coaxial (CCx) model, considering short-term behavior when laminar flow is experienced in the annular space of a coaxial heat exchanger. The discussion on pipe sizes is then expanded upon using the suggested model along with a modified design procedure to compare the performances realized by an example heat pump. A comparison is made here between configurations having various nominal inner pipe diameters while maintaining the same outer pipe. The results of the analysis show that increasing the inner pipe diameter, within the verified limit of the composite coaxial model, will reduce the required length of heat exchanger and increase the overall coefficient of performance realized by the heat pump.

While the United States is no longer the global leader in primary energy consumption, it still represents a significant percentage of global consumption. Residential buildings account for 22% of U.S. national primary energy consumption. Research efforts improving efficiency of existing U.S. homes will have opportunity to greatly impact national energy consumption by addressing a significant energy savings potential. Driving towards net-zero energy buildings provides an ideal scenario where homes produce all energy demands on-site. A joint research project, the ReNEWW House, captured an approach of renovating a home to net-zero energy. An efficient and advanced, hybrid air-hydronic HVAC system was installed. During the first heating season, excessive heat pump short-cycling occurred from improper buffer tank controls by default manufacturer settings. Modifications to the temperature control strategy recorded lower energy use through an improved heating system effectiveness. Results were collected over two heating seasons from in-field measurements. During the first heating season, the heat pump used 5440 kWh of electricity at annual heating degree day (HDD) of 6080 °F-day. The second season measured 3920 kWh of electricity at annual HDD of 4800 °F-day. The effectiveness for the heating season increased from 0.89 kWh/°F-day for the first season to 0.82 kWh/°F-day for the second.

This study aims to investigate the effect of demand response (DR) actions on energy consumption and energy cost with two alternative heat generation systems in a detached house in a cold climate. The heat generation systems are a ground source heat pump coupled with a two-storage tank system (GSHP heating system) and a water-based electric heating system coupled with a similar storage tank system (storing electric heating system). Four rule-based DR control algorithms were applied and studied for two alternative heat generation systems. Two rule-based DR control algorithms from previous study were applied and investigated for these heat generation systems based on real-time hourly electricity price and future hourly electricity prices based on the blocking-maximum subarray method. Two new rule-based DR control algorithms based on future hourly electricity prices were developed and investigated for these heat generation systems based on the sliding-maximum subarray method and moving average method. This research was implemented with the validated dynamic building simulation tool IDA ICE. The obtained results show that the maximum annual savings in the heating energy and cost take place using the rule-based DR control algorithm based on the sliding-maximum subarray method. As well, these savings are about 10% and 15%, respectively, for the GSHP heating system; and about 1% and 8%, respectively, for the storing electric heating system.

Having great resources of fossil fuels in Iran and ease of access to them inhibits utilization of renewable energies, especially in large scales. In spite of great sources of fossil fuels, Sistan province in the southeast of Iran has no gas pipelines yet and people sometimes use gas cylinders or oil products for heating of their houses. This paper aims to propose a sustainable renewable energy system to provide heating systems for residential buildings as well as domestic hot water (DHW). Five different combinations of solar assisted ground source heat pump (SAGSHP) are simulated for a residential building in the city of Zahedan, Iran. Modeling, simulation, and operation controlling have been performed in TRNSYS software and the coefficient of performance (COP), electrical power consumption of the GSHP, soil temperature, as well as building and domestic hot water temperatures for 10 years of operation have been obtained and compared. It is obtained that a 12 kW GSHP with the assisted flat solar collectors can supply space heating demand and DHW for the building throughout the winter. The maximum and minimum annual mean COP values are 3.75 and 3.52, respectively. In the best scenario for the system assisted with the solar collector, the energy consumption diminishes 8.7% compared to GSHP standalone system.