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The empirical success of the Artificial Intelligence (AI), has enhanced importance of the transparency in black box Machine Learning (ML) models. This study pioneers in developing an explainable and interpretable Deep Neural Network (DNN) model for a Guideless Irregular Dew Point Cooler (GIDPC). The game theory based SHapley Additive exPlanations (SHAP) method is used to interpret contribution of the operating conditions on performance parameters. Furthermore, in a response to the endeavours in developing more efficient metaheuristic optimisation algorithms for the energy systems, two Evolutionary Optimisation (EO) algorithms including a novel bio-inspired algorithm i.e., Slime Mould Algorithm (SMA), and Particle Swarm Optimization (PSO), are employed to simultaneously maximise the cooling efficiency and minimise the construction cost of the GIDPC. Additionally, performance of the optimised GIDPCs are compared in both statistical and deterministic way. The comparisons are carried out in diverse climates in 2020 and 2050 in which the hourly future weather data are projected using a high-emission scenario defined by Intergovernmental Panel for Climate Change (IPCC). The results revealed that the hourly COP of the optimised systems outperform the base design. Although power consumption of all systems increases from 2020 to 2050, owing to more operating hours as a result of global warming, but power savings of up to 72%, 69.49%, 63.24%, and 69.21% in hot summer continental, Arid, tropical rainforest and Mediterranean hot summer climates respectively, can be achieved when the systems run optimally.

Among all available solar technologies, solar-assisted heat pump (SAHP) is the most popular technology for low- and medium-temperature applications, i.e., drying, space heating, and water heating. This paper presents a critical review of the SAHP, leading to identification of the key technological challenges with the current SAHP technology, including (1) poor energy performance at low ambient temperatures; (2) difficulty in coupling solar thermal panels with heat pumps to achieve increased operational time and reduced electrical energy usage; (3) mismatch between heat demand of the building and heat supply of the SAHP system; and (4) lack of multi-functional modelling tool. A recently developed SAHP technology is introduced, which can effectively tackle the challenges with the current SAHPs, thus achieving enhanced solar efficiency, improved heat pump energy efficiency, and fast responsive time to the heat demand of buildings. The future research directions of the SAHP were identified: (1) multi-source heat pump; (2) heat pump defrosting capacity using waste heat and renewable energy; (3) advanced heat storage and exchange unit (HSEU) technology; and (4) advanced machine learning and multi-objective evolutionary optimisation models for performance prediction and optimisation of the SAHP using big datasets.

By analyzing the temperature distribution cloud image of the solar cell, it was found that the temperature distribution was uneven and there was a large temperature gradient, resulting in reduced effective cell size requiring a dual inlet model. At the same time, simulations and experiments were established, and it was found that the simulation results were consistent with the experimental results. This paper offers the first law of thermodynamics efficiency and exergy analysis of a simple optimized model at different inlet flow, concentration ratios and inlet temperatures. The result shows that while the inlet flow is 0.02–0.06 kg/s, the system runs efficiently, which can provide considerable heat output, and has greater protection for the cell. When the concentration ratio increases, thermodynamic efficiency and exergy efficiency will decrease, but the total output exergy is in an increasing trend and the trend will decrease as the concentration ratio increases. As the temperature of cooling water increases, the thermal and overall exergetic efficiencies will also increase, and when the inlet temperature is 60 °C, the electrical efficiency is still greater than 20%. In practical applications, the quality of thermal energy can be improved by increasing cooling water temperature, broadening the field of application.

Owing to the intermittent and fluctuating nature of solar energy, thermal energy storage (TES) plays a vital role in solar energy utilization. The structural and geometric limits of the traditional heat storage systems, as well as the low thermal conductivity of phase change materials (PCMs), decrease the heat storage and exothermic efficiency of TES severely. To alleviate these shortcomings and improve the TES heat storage and release efficiency, the geometrical structure of TES and fin structure of the heat storage system need to be optimized. This study established a 2D model of the phase change TES unit with a single tank and auxiliary electric heating based on the experimental findings. The heat transfer performance of the truncated cone model with different taper configurations was also analyzed numerically. The influence of long and short fins on PCM heat transfer was analyzed under the premise of a certain fin volume. The influence of fins with different inclinations on the heat transfer process was also analyzed. The results show that the truncated cone with a taper of 0.37 performs best in the charging and discharging process. Compared with long fins, most short fins showed to have a more significant effect on accelerating the charging process. The enhancement effect of the different fin on the heat transfer process was divided into two categories, and the analysis shows that the fins with an inclination angle of −15° have the most significant enhancement effect. These findings of the study will guide the optimization design of the heat transfer structure of TES with a single tank configuration.

A novel dual source vapor injection heat pump (DSVIHP) using exhaust and ambient air is proposed. The air exhausted from the building first releases energy to the medium-pressure evaporator and is then mixed with the ambient air to heat the low-pressure evaporator. A vapor injection (VI) compressor of two inlets is connected with the low and medium pressure evaporators. It's first time that a VI compressor is employed to recover the ventilation heat. The system can minimize the ventilation heat loss and provide a unique defrosting approach by using the exhaust waste heat. Fundamentals of the proposed DSVIHP are illustrated. Mathematical models are built. Both energetic and exergetic analyses are carried out under variable conditions. The results indicate that the DSVIHP has superior thermodynamic performance. The superiority is more appreciable at a lower ambient temperature. It has a higher COP than the conventional vapor injection heat pump and air source heat pump by 11.3% and 23.2% respectively at an ambient temperature of -10 °C and condensation temperature of 45 °C. The waste heat recovery ratio from the exhaust air is more than 100%. The novel DSVIHP has great potential in the cold climate area application.

In order for a solar heating system to provide heat immediately after sunrise, a fast response is needed to the heat demand of a serviced space. The majority of existing solar heating systems have a slow response time due to the large volume of water stored in the heat storage/exchanger unit (HSEU). This leads to a slow heat delivery cycle, which results in discomfort for the occupants and thus creates a huge barrier to the wide deployment of solar heating systems. To overcome this critical issue, a novel interactive heat storage/exchanging unit (HSEU) employing a double-tank configuration was developed. Unlike conventional HSEUs, which have a single tank acting as the heat storage and exchanging unit, the new HSEU is comprised of a small tank for heat exchange combined with a large tank for heat storage. The small tank enables fast transfer of solar heat to the heating loop fluid without having to heat up the large volume of water in the entire HSEU tank, whilst the large tank is used to store and exchange heat between itself and the small tank using a temperature-oriented control mechanism. To test the proposed design, the heat transfer between the first (solar loop) and second (heating loop) fluids, the heat and mass transfer between the small and large tank and the associated operational strategy were investigated experimentally and theoretically for comparison. A conventional single tank HSEU requires around 120 min to deliver heat to a served space, whilst the new interactive double-tank HSEU can provide heat to the served space in around 20 min, thus creating a heating system which can respond significantly faster than traditional systems. The investigation of the heat exchange effect between the solar and heating loop fluids showed that the new HSEU achieved a convective heat transfer coefficient of as high as 391 W/m2·K, which is 551% higher than that of a conventional tank. As a result, the solar thermal efficiency of the solar panel-array in the new HSEU

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.

This study presents a detailed three-dimensional numerical investigation of the optimum thermoelectric geometry in a hybrid concentrated photovoltaic-thermoelectric system under varying weather conditions. Four different thermoelectric leg geometries are considered and their effects on the performance of the hybrid system are studied. The effects of thermoelectric leg height, cross-sectional area and ceramic height on the hybrid system performance are investigated. Furthermore, the effect of convective heat transfer coefficient on the hybrid system performance is studied. The performance of the hybrid system with optimized thermoelectric geometry is compared with that of the hybrid system with original geometry for summer climatic conditions in London, United Kingdom for a duration of 24 h. Results show that thermoelectric geometry optimization can reduce significantly, the negative impacts of the variable weather conditions on the hybrid system performance. Furthermore, results show that the maximum hybrid system power output density with the optimized thermoelectric geometry decreased by 48.29% when the original geometry is used. This study will provide useful insights into thermoelectric geometry optimization in a hybrid system and optimum thermoelectric geometry for performance enhancement.

An efficient low-carbon system is proposed to meet the heating and cooling demands of rural houses in cold regions. Mini-channel solar panels incorporating a novel multiple-throughout-flowing loop are used for heat collection, whilst a vapour injection air source heat pump (VI-ASHP) is innovatively combined with an underfloor heating and cooling system. To demonstrate the system, a multiple-throughout-flowing mini-channel solar thermal panel array of 36 m2 and a VI-ASHP of 40 kW heating capacity have been built and tested. Subsequently, mathematical models of the solar-assisted VI-ASHP system are established and compared with the experimental data. Based on the validated models, the energetic, economic and environmental performance is investigated under the typical weather conditions for a northern Chinese city (Taiyuan). The results indicate that, for a common rural house employing the proposed novel system, the proportion of the annual heat requirement, cooling load and hot water heating energy provided by solar thermal energy, photovoltaic energy and electricity from the power grid is 74.6%, 6.9%, and 18.5% respectively, thus giving a total energy supply proportion of 81.5% from solar energy. In addition, compared with a coal-powered system, our system has a cost payback period of 6.52 years and a life-cycle net cost saving of 56328.4RMB, thus the proposed system provides a greater economic performance. Furthermore, it can save 5tons of anthracite coal and reduce carbon emissions by 12.1tons annually. The proposed solar-assisted VI-ASHP has the potential to fulfil heating and cooling demands whilst reducing carbon emissions in northern China.

This paper presents a whole building energy modelling work incorporating a state-of-the-art indirect evaporative cooling system. The model is calibrated and validated with real-life empirical data, and is capable of representing actual performance of the system with high reliability. The investigated system is a novel super-performance Dew Point Cooler (DPC) with a guideless and corrugated Heat and Mass Exchanger (HMX). The DPC is modelled as part of the whole building energy model through detailed description of system and building characteristics at source code level. The developed model has been simulated in all different climates that an Indirect Evaporative Cooling (IEC) system can be operated, namely: subtropical hot desert, humid continental, Mediterranean, and hot desert climates. The performance predictions has been tested against experiments and numerical model of the same system, and a detailed investigation of modelling approaches to efficiently and effectively model aforementioned systems has been provided. The calibrated and empirically validated whole building energy model predicted the key performance parameters of the dew point evaporative cooling system with mean error values limited to 4.1%. The highest COP values recorded by experiments and whole building energy simulations were 51.1 and 49, respectively. The whole building energy model proved to better predict the performance of dew point evaporative cooler, when compared to numerical models, by incorporating the building-side parameters into the model. This modelling work paves the way toward detailed investigation of the advanced cooling systems within building context to achieve optimised performance of the system in wide range of buildings and operating conditions.

This study is pioneered in developing digital twins using Feed-forward Neural Network (FFNN) and multi objective evolutionary optimization (MOEO) using Genetic Algorithm (GA) for a counter-flow Dew Point Cooler with a novel Guideless Irregular Heat and Mass Exchanger (GIDPC). The digital twins, takes the intake air characteristics, i.e., temperature, relative humidity as well as main operating and design parameters, i.e., intake air velocity, working air fraction, height of HMX, channel gap, and number of layers as the inputs. GIDPC’s cooling capacity, coefficient of performance (COP), dew point efficiency, wet-bulb efficiency, supply air temperature and surface area of the layers are selected as outputs. The optimum values of aforementioned operating and design parameters are identified by the MOEO to maximise the cooling capacity, COP, wet-bulb efficiencies and to minimise the surface area of the layers in four identified climates within Köppen-Geiger climate classification, namely: tropical rainforest, arid, Mediterranean hot summer and hot summer continental climates. The system monthly and annual performances in the identified optimum conditions are compared with the base system and the results show the annual improvements of up to 72.75% in COP and 23.57% in surface area. In addition, the annual power consumption is reduced by up to 49.41% when the system is designed and operated optimally. It is concluded that identifying the optimum conditions for the GIDPC can increase the system performance substantially.

Swift performance assessment of dehumidification systems, in design stage and while operation of the system is of substantial importance for commercialization and wide implementation of this technology. This paper presents a novel statistical model, employing Gaussian Process Regression (GPR) to investigate performance of a solar/waste energy driven dehumidification/regeneration cycle with a solid adsorbent bed. The statistical model takes thousands of operating conditions derived from a numerical model to predict the performance of the system. This predictive tool directly correlates the main operating parameters with the performance parameters of the system. The operating parameters considered in this study are: temperature, relative humidity and flow rate of process air, temperature of regeneration air, length of the desiccant bed, solar radiation intensity and operating time, and the selected performance parameters are: moisture extraction efficiency for the dehumidification cycle and moisture removal efficiency for the regeneration cycle. The model is evaluated by three metrics, namely: root mean square error (RSME), mean absolute percentage error (MAPE), and coefficient of determination (R2). The maximum RSME and MAPE for moisture extraction are only 0.045, 0.21%, and for moisture removal efficiencies are 0.082 and 0.39%, respectively, while the R2 value is derived as 0.97. The developed model is used to investigate the impact of four selected operating parameters on system performance. Additionally, the system performance is predicted for randomly generated operating conditions as well as warm and humid climates. The developed GPR model provides a swift and highly accurate predictive tool for design of the dehumidification systems and for commercialization of the investigated dehumidification systems.

The world's perennial need for energy and microelectronic miniaturization brings with it a broad set of technological and scientific challenges. Materials characterized by precise microstructural architectures based on fractal analysis and ranging in size down to nano scale represent an important avenue for finding novel solutions. Deep materials structure hierarchies of this type open new possibilities in capacity according to the Heywang model, especially when extended by a fractals approach and intergranular relationships supported and recognized by their fractal nature. These developments are opening new frontiers in microelectronics miniaturization. They build on early fractal applications that were used as tools in miniaturization research and also provided application perspectives for diverse energy technologies. In other words, fractals, as a crucial concept of modern theoretical-experimental physics and materials sciences, are tightly linked to higher integration processes and microelectronics miniaturization. They also hold potential for meeting the energy exploitation challenge. In this research context, for the first time we experimentally and theoretically investigated the electrostatic field between the grains within fractal nature aspects. It is essentially a theoretical experiment based on samples of experimental microstructures imaged with SEM, as previously published in a number of other papers. We now take the research a step further by consolidating the experimental samples with respect to the predicted distribution of grains and pores within the sample mass. We make an original contribution by opening the frame of scale sizes with respect to the technical processes of consolidation. This lets us predict the constitutive elements of the microstructures – approximately equidistant grains and pores. In this paper we define in a practical manner the final target elements for experimental consolidation of real samples. It is the main bridge between a

Many cities across the world have the ambition of becoming carbon neutral, but exact figures of progress toward that goal are limited. Regarding Europe’s not overly ambitious 2020 carbon emission targets, many countries still have a long way to go (see Fig. 1), with cities as the prime objects for improvement. It is fair to say that the energy transition is lagging behind, for which several reasons can be given. One assumption, based on experience with projects with various European cities, is that cities—their administrations and other stakeholders—generally have insufficient understanding of how to gain and maintain control over the complex process of the energy transition with its multiple actors and diverse objectives and responsibilities. Another suggested reason is the lack of appropriate approaches, strategies, and methods to guide the energy transition in formulating clear targets and intermediate steps of mainly technical and spatial interventions. These, however are currently under development, and are being tested in cities across the continent—such as in Gothenburg, London, Rotterdam, Cologne, and Genova within the EU project Celsius (www.celsiuscity.eu), and in Amsterdam and Grenoble, for the EU project City-zen (www.cityzen-smartcity.eu)—with promising results so far. The main research question underlying this chapter is: How can cities be supported in their energy transition toward carbon neutrality? We will describe the development of approaches, strategies, and methods for the urban energy transition, their background and theoretical basis, and present urban case studies where they were applied. Finally, an outlook will be given for methodological developments in the near future.

This review of public perceptions of unconventional oil and gas exploration identifies four main types of study. First, UOG is analysed in terms of specific environmental and public health impacts. Second, by examining socioeconomic impacts (namely the development of energy boom-towns). Third, in terms of the relationship between prior knowledge of UOG technology and public attitudes of support or opposition. Fourth, in terms of framing and discursive analysis of UOG by stakeholder groups including the print media. We identify a specific knowledge gap for environmental health professionals: that research is needed into how public and environmental health messages can be best communicated to diverse communities potentially affected by fracking, in order to directly improve public health outcomes.

This article is focused on thermoelectric cooling (TEC) and thermoelectric power generation (TEG). Detailed theoretical modeling and characterization were presented with the key performance highlighted. Heat transfers from heat sinks on both hot and cold surfaces of the thermoelectric models were discussed and measures to enhance and increase heat transfer rates were proposed. Waste heat from the steel industry, vehicle exhaust gas and solar energy for TEG power generation were discussed. Two advanced technologies, i.e., two-stage TEG and heat pipe assisted TEG, were listed to increase the overall efficiencies of power generation.

The contributors to this special issue are from early carrier researchers to experts in their relative areas from across the world and represent a current and up to date research overview on functional nanomaterials in energy / environmental for a better society and nano-catalysis for green technology. The topics were the two important themes in our 1st International symposium entitled Functional Nanomaterials in Industrial Applications: Academic - Industry Meet (29-31 March 2016), University of Central Lancashire, Preston, United Kingdom. A special focus issue on theme 2 (Nanomedicine for Health and Diagnostics) will be published in the journal "Nanomedicine" by Future Medicine in November 2016.

Climate change will lead to more warm and hot days in the Netherlands. Climate adaptation measures are needed to reduce the vulnerability of urban areas. Moreover, proven adaptation measures, such as increased vegetated areas or water surfaces, are not always possible due to a lack of space or undesired aesthetic effects. An alternative option is to make use of coloured façades to create drafts and accelerate wind speed in a street canyon or on a square to attract fresh air from cooler places. Differences in colour and material types already influence the air flow in street canyons in an uncontrolled manner. If this thermal comfort principle can be implemented, it will potentially have a significant impact on many cities throughout the world. This paper presents the results of a first exploratory research based on measurements on scale models and at full scale. This pilot study indicates success of the intended draft principle, advocating further research.

Due to the increasing size and flexibility of large wind turbine blades, accurate and reliable aeroelastic modelling is playing an important role for the design of large wind turbines. Most existing aeroelastic models are linear models based on assumption of small blade deflections. This assumption is not valid anymore for very flexible blade design because such blades often experience large deflections. In this paper, a novel nonlinear aeroelastic model for large wind turbine blades has been developed by combining BEM (blade element momentum) theory and mixed-form formulation of GEBT (geometrically exact beam theory). The nonlinear aeroelastic model takes account of large blade deflections and thus greatly improves the accuracy of aeroelastic analysis of wind turbine blades. The nonlinear aeroelastic model is implemented in COMSOL Multiphysics and validated with a series of benchmark calculation tests. The results show that good agreement is achieved when compared with experimental data, and its capability of handling large deflections is demonstrated. Finally the nonlinear aeroelastic model is applied to aeroelastic modelling of the parked WindPACT 1.5 MW baseline wind turbine, and reduced flapwise deflection from the nonlinear aeroelastic model is observed compared to the linear aeroelastic code FAST (Fatigue, Aerodynamics, Structures, and Turbulence).