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• Numerical model for a four-layer CdTe-based VPV glazing was developed. • The model was validated experimentally with a U-value of 0.92 W/(m2⋅K). • About 60% heat loss and heat gain can be reduced by VPV in cold and hot climates. • More than 40 kWh/m2 average power generation of VPV windows can be achieved. Vacuum-photovoltaic (VPV) glazing has attracted much attention due to its excellent thermal insulation performance and its ability to utilize solar energy. However, few simulation models have been established based on actual products and rarely have been validated by experiments. In this paper, a four-layer CdTe-based VPV glazing was developed and the corresponding numerical heat transfer model was established with the integration of a dynamic power generation model. The numerical model was then validated against both the results from the WINDOW program and a guarded hot box experiment. Afterward, the validated model was employed to analyze the energy and power generation performance of the VPV glazing in diverse climate zones in China with Harbin, Beijing, Changsha, Guangzhou, and Kunming used as representative cities. The numerical simulation results indicate that the U-value of the proposed VPV glazing is 0.89 W/(m2⋅K), which is in good agreement with the experimental results. Compared with a normal double glazing, the average energy reductions achieved with VPV glazing in air conditioning seasons are 128 kWh/m2, 23 kWh/m2, 45 kWh/m2, and 52 kWh/m2 in Harbin, Beijing, Changsha, and Guangzhou, respectively. In addition, the average annual power outputs of VPV glazing in Harbin, Beijing, Changsha, Guangzhou, and Kunming are 47 kWh/m2, 48 kWh/m2, 34 kWh/m2, 36 kWh/m2, and 45 kWh/m2, respectively. The numerical model developed in this study can be used for energy-saving potential analysis and optimization of VPV glazing in different meteorological conditions, the results of which could provide guidance for the effective application of VPV glazing. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the yearly performance of a library building located in Harbin, China, equipped with a ground-coupled heat pump (GCHP) system, was simulated and its ground heat exchanger (GHE) was designed in the TRNSYS 17 environment. Utilizing the hourly load simulation results, a TRNSYS model was developed to analyze underground thermal balance of the entire system, obtaining the 30-year operation conditions of the reference building. According to simulation results, annual average storage temperature, the highest and lowest inlet temperature of the heat pump, factors that influence efficiency of the system, change as the number of boreholes changes. And the optimized length of heat exchangers was studied, as well as method of determining the concentration of antifreeze in heat-transfer fluid in cold regions. [Copyright &y& Elsevier]

• A solar lighting/heating system using spectrum-sensitive nanofluids was developed. • The light transmission efficiency was close to that of current solar lighting systems. • 1 m2 collection area provided 466.4 MJ of thermal energy in summer season. • The effect of operation condition on the system efficiency was explored. Solar lighting is considered as a promising technique, which has huge potential in conserving energy and relaxing the residents. However, current solar lighting systems used a filter to allow only visible light to enter buildings, releasing all the other energy contained in the long wave of the solar into the surrounding air. Such practice leaded to low efficiency of solar energy utilization and high costs. In this paper, a solar lighting/heating system was developed which used a hollow lens filled with ATO nanofluid to separate the long wave and short wave of solar energy. A series of tests were conducted to explore the performance of system. Results indicated that under the test condition of Case 1 (0.025%/0.0001% ATO/Graphite nanofluid, 100 L/h flow rate), the light transmission efficiency was 19.5% which was comparable to that of current solar lighting systems, and the heat absorption efficiency was 25.35%. The heat energy collected by the such a system from June to August (three months) in the city of Harbin was about 466.4 MJ in per square meter of collection area. The volume concentration of nanofluids had great influence on both the light transmission efficiency and the heat absorption efficiency. The flow rate had little influence on the light transmission efficiency, but had great influence on the heat absorption efficiency of the system. [ABSTRACT FROM AUTHOR]