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• Experimental performance analysis of a CO 2 DX-SAHP. • COP decreases when the water inlet temperature increases. • The augment of solar radiation increases COP. • COP slightly increases due to the humidity increases. In the past decades, combined solar energy with heat pump systems has been one of the very widespread ways to improve the efficiency of conventional heat pumps. In that way, this paper presents an experimental analysis of the influence of environmental conditions in a small size DX-SAHP operating with CO 2 as refrigeration fluid to heat water. The variation of the water inlet temperature, the solar radiation flux and the relative humidity are analyzed and 88 different experimental results are presented. To support the analysis, a thermographic camera was also used. The results show that the gas cooler outlet pressure and temperature are strongly influenced by the water inlet temperature. As the water inlet temperature increases, the gas cooler outlet pressure and temperature increase, and consequently the COP decreases. The COP decreases in 45.8% for the variation of the water inlet temperature to 15–35 oC. The variation of the solar radiation of 876.9–30.17 W.m-2 presents a reduction of performance in about 30%. For the same conditions for the water heat exchange, the pressure ratio of the cycle decreases with an augment on the solar radiation flux. In addition, the COP is higher in 6% for a change in the mean relative humidity of 31.6–55.8 %. [ABSTRACT FROM AUTHOR]

In this paper, the experimental study aims to enhance a distillate water productivity of solar stills. To achieve this objective, solar still with continuous water desalination along 24 h was designed, structured, and operated in the city of Tanta, Gharbia Governorate, Egypt. For the solar stills, the temperatures of the condensing surface are very low throughout the night and during the early hours of the morning. This advantage makes the uses of the solar stills with continuous desalination along 24 h to be more effective. To achieve the continuous water desalination, the electric water heater (EWH) was installed in the basin of solar still to heat the basin water in the night and during the early hours of the morning. The EWH is powered by solar batteries that are charged by PV panels during sunrise. The experimental results presented that the accumulated distillate water productivity for using the continuous water desalination along 24 h varied between 10,631 and 12,087 mL m−2 day−1 after period use of 2 May to 11 August. The improvement in accumulated productivity of solar still with continuous water desalination along 24 h varied between 159.3 and 177.9% as compared to solar still working without EWH. Also, the improvement in the overall efficiency of solar still with continuous water desalination varied between 27.9 and 31.3%. [ABSTRACT FROM AUTHOR]

In pursue of energy-efficient alternative water heating options, a SWOT-AHP analysis was accomplished for Solar Water Heater (SWH) and Heat Pumps (HP) against instantaneous water heaters (IWH). The results show that the energy consumption and bills saving are dominant in strength of both HP and SWH. Financial and technological aspects seem to play a relatively significant role. Additionally, HP and SWH are more convenient for the energy consumption in water heating technology in hotel sector of Thailand. Finally, we can say that HP and SWH are more convenient for water heating system as compare to IWH. [ABSTRACT FROM AUTHOR]

Domestic hot water production is responsible for a significant part of domestic energy consumption; instantaneous gas heating devices are widely used because they don't require reservoirs, therefore have a competitive use/consumption ratio compared to other technologies. However, users' perception of comfort is severely affected by sudden changes in temperature outside the desired temperature. The instability of the water temperature with overshoots and undershoots is the most common disadvantage, which occurs mainly due to sudden changes in the water flow requested by users and the response delays inherent to the heating system. Traditional heat cell power controllers have difficulties in responding to these problems in a timely manner, as they don't have the capacity to anticipate the effects of sudden variations in water flowrate. In this work, predictive control strategies were developed which, due to its predictive nature, allows anticipating and correcting the negative effects of sudden variations of water flowrate in the temperature. A comparative analysis of model based predictive controllers (MPCs), with and without adaptive function, with traditional controllers used in the tankless gas water heaters (TGWHs) was carried out. Tests in a simulated environment demonstrated better performances in the stabilization of temperature during sudden changes in water flowrates. [ABSTRACT FROM AUTHOR]

Summary: The current research experimentally investigated a sustainable desalination method to maximize freshwater production at minimal costs. Solar photovoltaics are used as a source of clean and renewable energy. The system used in conducting the experiments consists of: an air heater, water heater, two stages of cross‐flow humidification, two stages of cross‐flow dehumidification, and an oxy‐hydrogen gas generator. The setup's working principle is the open‐air and closed water cycle. A centrifugal fan blows the ambient air to pass through the air heater. Air is heated through a heat exchanger, which is consequently heated by hot water. Water is heated using a new heating approach by using a mixture of 20% natural gas and 80% hydrogen gas with less impact on environmental pollution. Air is then humidified through two‐stage humidification systems using a high water temperature technique, then through the innovative vibrating plate circuit, respectively. The humidified air is condensed through two consecutive dehumidification heat exchangers. The system parameters are optimized to enhance freshwater productivity. The studied operative parameters are air mass flow rate, water mass ratio (WMR), and the effect of adding a second stage of humidification. The results showed that the maximum daily productivity is 49.3 kg/day. The optimum air mass flow rate and water mass ratio to obtain maximum productivity was found to be 0.375 kg/s and 0.6, respectively. Furthermore, the experiments' results showed that two‐stage humidification enhanced freshwater productivity by 23.25% than that of the single stage of humidification. Finally, an economical study analysis conducted for the test rig showed the cost per liter to be 0.0114 $/L, which is competitive when compared with previous work. [ABSTRACT FROM AUTHOR]

While home energy prices keep rising, homeowners nowadays are searching for the right options to reduce their electricity bills. Besides, the increase in power consumption can contribute to environmental pollution. Therefore, the proper management of energy in the domestic sector is a vital element for creating a sustainable environment and cost reduction. In this study, the most domestic household appliances consumption of energy are modelled and analysed using the fuzzy logic controller (FLC) in order to permit the home energy management system (HEMS) to perform energy utilization estimation and cost analysis. These appliances are the heating ventilation and air conditioning (HVAC), electric water heater (EWH), and lighting, respectively. The developed system can help to analyse the appliances' energy consumption and cost sceneries during peak and off-peak hours. The modelling of a fuzzy-based domestic appliances controller for HEMS takes the peak and non-peak tariff of Malaysian grid into consideration. The simulation results demonstrate that the developed models are able to manage energy consumption and cost reduction efficiently. By using the proposed FLC, the cost of energy is reduced by 21.75 %, 30.77 %, and 41.96 % for the HVAC, EWH, and dimmable lamps, respectively. In sum, the FLC shows good performance to reduce the cost and power consumption toward efficient HEMS. [ABSTRACT FROM AUTHOR]

A single-effect absorption cooling system was planned and simulated appropriate to a hot and dry climate, and optimization was made accordingly in the present study. TRNSYS software is a very comprehensive program that includes much equipment in its subprograms. For this reason, solar collectors, cooling tower, auxiliary heater, and storage tank used in this study are modeled in this software. The designed cooling system is considered as a market that has a cooling need of 35 kW and has a space of 275 m2. It was examined in this study that how the performance of a single-effect LiBr-H2O absorption cooling system was affected by three different kinds of solar collectors such as flat plate collector (FPC), Non-tracking concentrating parabolic solar collector (XCPC), and evacuated tube collector (ETC). It was also evaluated that how different criteria such as solar fraction, hot water tank temperature and tank volume, collector area, and collector type affected system performance. In the study, it was noticed that collector area had an important effect on the collector efficiency, heater power and hot water tank temperature. It was found that minimum collector area for XCPC, ETC and FPC collectors were approximately 100 m2, 125 m2 and 150 m2, respectively. Also, depending on the change in the tank volume, significant changes occurred in the tank temperature. The hot water tank volume was raised from 0.5 m3 to 6 m3 for XCPC, ETC and FPC collectors, the upper hot water tank temperature decreased about 15°C, 11°C and 8°C, respectively. In conclusion, it has been observed that XCPC collectors perform better to improve system performance compared to other collectors used. [ABSTRACT FROM AUTHOR]

Copyright of Transactions the Japan Society of Refrigerating & Air Conditioning Engineers is the property of Japan Society of Refrigerating & Air Conditioning Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Japan's long-term strategy submitted to the United Nations Framework Convention on Climate Change emphasizes the importance of improving the electrification rates to reducing GHG emissions. Using the five models participating in Energy Modeling Forum 35 Japan Model Intercomparison project (JMIP), we focused on the demand-side decarbonization and analyzed the final energy composition required to achieve 80% reductions in GHGs by 2050 in Japan. The model results show that the electricity share in final energy use (electrification rate) needs to reach 37–66% in 2050 (26% in 2010) to achieve the emissions reduction of 80%. The electrification rate increases mainly due to switching from fossil fuel end-use technologies (i.e. oil water heater, oil stove and combustion-engine vehicles) to electricity end-use technologies (i.e. heat pump water heater and electric vehicles). The electricity consumption in 2050 other than AIM/Hub ranged between 840 and 1260 TWh (AIM/Hub: 1950TWh), which is comparable to the level seen in the last 10 years (950–1035 TWh). The pace at which electrification rate must be increased is a challenge. The model results suggest to increase the electrification pace to 0.46–1.58%/yr from 2030 to 2050. Neither the past electrification pace (0.30%/year from 1990 to 2010) nor the outlook of the Ministry of Economy, Trade and Industry (0.15%/year from 2010 to 2030) is enough to reach the suggested electrification rates in 2050. Therefore, more concrete measures to accelerate dissemination of electricity end-use technologies across all sectors need to be established. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water heating is a main consumer of energy in households, especially in temperate and cold climates. In South Africa, where hot water is typically provided by electric resistance storage tank water heaters (geysers), water heating energy consumption exceeds cooking, refrigeration, and lighting to be the most consumptive single electric appliance in the home. A recent analysis for the Department of Trade and Industry (DTI) performed by the authors estimated that standing losses from electric geysers contributed over 1,000 kWh to the annual electricity bill for South African households that used them. In order to reduce this burden, the South African government is currently pursuing a programme of Energy Efficiency Standards and Labelling (EES&L) for electric appliances, including geysers. In addition, Eskom has a history of promoting heat pump water heaters (HPWH) through incentive programs, which can further reduce energy consumption. This paper provides asurvey of international electric storage water heater test procedures and efficiency metrics which can serve as a reference for comparison with proposed geyser standards and ratings in South Africa. Additionally it provides a sample of efficiency technologies employed to improve the efficiency of electric storage water heaters, and outlines programs to promote adoption of improved efficiency. Finally, it surveys current programs used to promote HPWH and considers the potential for this technology to address peak demand more effectively than reduction of standby losses alone

Purpose: This paper aims to identify key service attributes in peer-to-peer (P2P) accommodation from online reviews and formulate service improvement strategies based on the unsatisfactory service encounters mined from the reviews. Design/methodology/approach: The methodology involves topic modelling using latent Dirichlet allocation, sentiment analysis and process analysis based on process chain network (PCN). Findings: The text analytics results showed that negative P2P accommodation experiences are caused by the lack of hot water for shower, poor sleep quality and unpleasant check-in. Research limitations/implications: The PCN analysis shows that the surrogate interactions of the P2P accommodation platform with both the guest and the host impact consumer experiences. This highlights that the key to managing consumer experiences lies in the non-human resources such as information, rather than direct interactions between process entities. Practical implications: The information on the P2P accommodation platform should be in a more interactive format such as video and 360 degrees camera. Hosts should ensure a good condition of the physical products such as water heaters and beds before guests' arrival. Professional videography and handyperson services should be provided by the platform to help hosts deliver a preferred consumer experience. Flexible and strict check-in polices should also be introduced to smoothen the check-in process. Originality/value: This study is built on multi-attribute utility theory. It is also one of the first to study P2P accommodation services from an operations management perspective. It demonstrates how text analytics serves as an additional supplement for service improvement. [ABSTRACT FROM AUTHOR]

The article reflects the preliminary results of research on the topic. It substantiates the effectiveness of replacing the system of energy devices used in the heating of buildings, operating based on traditional energy carriers, with fundamentally different systems that are environmentally friendly and inexhaustible, fed from alternative energy sources. The interrelated problems of energy saving and energy efficiency are equally important, and based on the analysis of the experience of developed countries, the ways to address the issues that need to be addressed in this direction in our country have been identified. [ABSTRACT FROM AUTHOR]

A cogeneration solar system for a building located in Sabzevar (Iran) is investigated in this study. In this system, a combination of a solar evacuated tube collector field and an auxiliary natural gas burner drive a single effect absorption chiller. Solar energy is also used to produce consuming hot water. Hourly cooling demands of the building were calculated during April to September. In order to perform a more obvious assessment, important parameters such as COP and efficiencies were obtained based on the total cooling load, the total amount of absorbed solar energy and consumed natural gas, and the total produced hot water during April to September. Energetic, exergetic, and economic analyses were performed in order to find the most efficient generator temperature. Considering the results, the minimum consumption of natural gas happened at a generator temperature of 104 ° C while the highest chiller exergy efficiency is observed at the generator temperature of 97 ° C. Also by assuming the required gas fuel to supply the consuming hot water -which is produced by solar energy-as a saving parameter, the economic optimum generator temperature to drive the absorption chiller and to supply the consuming hot water is obtained at the generator temperature of 96 ° C. • Presenting a transient model of a solar-gas driven absorption chiller integrated with a consuming water heater. • Considering the hourly variations of cooling load and solar radiations. • Obtaining the most efficient generator temperature based on energetic, exergetic and economic concerns. [ABSTRACT FROM AUTHOR]

The utilization of a hybrid energy system (combined solar water heater (SWH) and an air source heat pump (ASHP) water heater) can result in over 80% reduction in the electrical energy consumed as the system is capable to operate with an energy factor of above 4.0. A major challenge is to develop credible methodology or mathematical model to predict energy savings. The research focused on the design and installation of a hybrid energy system and a data acquisition system to monitor its performance. The average weekday volume of hot water consumed, thermal energy gained by water in the tank of the air source heat pump (ASHP) water heater, electrical energy consumed, and the COP were 225.03 L, 5.25 kWh, 1.52 kWh, and 3.50. The average weekday global solar radiation, ambient temperature, solar fraction of the solar water heater (SWH) and the energy factor of the hybrid energy system were 579.67 W/m2, 23.58°C, 0.52, and 4.02, respectively. A multiple linear regression model was developed to predict the energy factor of the hybrid energy system. Both the modelled and validated results showed very good determination coefficients of 0.952 and 0.935, with the trained and validated dataset. Hence, by employing both multiple linear regression model and a multiple 2D contour plot simulation, the energy factor and the variation of the input parameters can be accurately determined. The developed model can help homeowners, energy service companies, and policy makers to appreciate and confidently support the rollout of the technology for sanitary water heating. [ABSTRACT FROM AUTHOR]

Air source heat pump (ASHP) water heaters are efficient devices for sanitary hot water heating. The coefficient of performance (COP) of the air to water heat pump (AWHP) is constantly lower than that of the corresponding ASHP unit. The study focused on determining the COP of both the ASHP unit and the AWHP. This was achieved by the implementation of both experimental and simulation methods, with the help of a data acquisition system and the REFPROP software. The system comprised of a 1.2 kW split type ASHP unit and a 150 L high pressure geyser. A power meter, flow meters, temperature sensors, pressure sensors, ambient temperature and relative humidity sensor were installed at precise locations on the split type AWHP. Controlled volumes of 150, 50 and 100 L were drawn off from the AWHP during the morning, afternoon and evening for a year. The average COP for the summer and winter, in terms of the input electrical and output thermal energies of the AWHP were 3.02 and 2.30. The COPs of the ASHP unit, in terms of the change in the enthalpies of the refrigerant at the inlet and the outlet of the condenser and the evaporator, were 3.52 and 2.65 respectively. The study showed that the difference between the COP of the ASHP unit and that of the AWHP could be ascribed to the electrical energy consumed by the fan and the water circulation pump during the vapour compression refrigeration cycles. The work provides an energy optimisation opportunity to the manufacturers of this technology, helping to enhance the efficiency and COP of ASHP water heaters. [ABSTRACT FROM AUTHOR]

The article herein presents a new technique of controlling the system of collecting, storing and processing the information from the solar collectors, which might be applied to heating the industrial and domestic compartments for hot water supply. The most profitable usage of the solar collectors in the industry is replacement of a human interference with wireless sensor nets. The solar collector standard system consumes in average 30% of the heat due to poor control and configuration. Our monitoring and control system allows upgrade the performance of heating the industrial and domestic premises by means of solar collector for hot water supply. [ABSTRACT FROM AUTHOR]

A simulation with TRNSYS of an individual solar water heater for the hot water needs of an average family in Algeria was made; three cities of different climates were chosen to the north on the coast, in the highlands and in a desert region, the solar water heater consists of a flat panel of 4m² and a storage tank of 300 liters, a back-up electrical energy is activated when solar radiations are insufficient or during the night, the consumption of domestic hot water leaving the tank at 60°C follows a typical profile, the results show significant performance in the south and similar data in the north and in the highlands. [ABSTRACT FROM AUTHOR]