The design of the novel PV-Trombe wall in Hefei is theoretically processed in this paper. The area of winter air vents and width of PV-Trombe wall are determined, the effects of two improvements (thermal insulation and shading curtain) are investigated, and the different operating results for winter heating and summer cooling are also obtained. Results show that if compared to the original PV-Trombe wall, after thermal insulating, the indoor temperature increases by $2.36°C$ in winter and decreases by $2.47°C$ in summer and the electrical efficiency decreases by $<2%$. After curtain shading, the indoor temperature decreases by $2.00°C$ in summer and the electrical efficiency increases by $∼1%$. It is recommended that thermal insulation in both winter and summer and appending a shading curtain in summer are adopted for PV-Trombe wall, especially for the diurnally used PV-Trombe wall.

Evacuated tube solar water heater systems are widely used in China due to their high thermal efficiency, simple construction requirements, and low manufacturing costs. CPC evacuated tube solar water heaters with a geometrical concentration ratio C of less than one are rare. A comparison of the experimental rig of evacuated tube solar water heater systems with and without a mini-CPC reflector was set up, with a series of experiments done in Hefei (31°53'N, 117°15'E), China. The first and second laws of thermodynamics were used to analyze and contrast their thermal performance. The water in the tank was heated from 26.9 to 55, 65, 75, 85, and 95 °C. Two types of solar water heater systems were used, and the data gathered for two days were compared. The results show that when attaining low temperature water, the evacuated tube solar water heater system without a mini-CPC reflector has higher thermal and exergy efficiencies than the system with a mini-CPC reflector, including the average and immediate values. On the other hand, when attaining high temperature water, the system with a mini-CPC reflector has higher thermal and exergy efficiencies than the other one. The comparison presents the advantages of evacuated tube solar water heater systems with and without a mini-CPC reflector, which can be offered as a reference when choosing which solar water system to use for actual applications.

An improved Trombe wall is proposed to adapt to building construction with selective thermo-insulation façades (internal and cavity wall insulation, but not external wall insulation system). The case study is conducted in Xining, Capital city of Qinghai province in China, where the general building façades are mostly selective thermo-insulation façades to fight against the severe cold. A numerical analysis is undertaken to show the effects on the improvement of the building’s thermal environment by comparing the improved Trombe wall system with the classical Trombe wall system. The operating efficiency of the improved Trombe wall can be up to 33.85%, an increase of 56%. The results show that the improved Trombe wall works more effectively than the classical Trombe wall system in utilizing solar energy for the sample building.

This study aims to understand the transport and dispersal of droplets produced by coughing in a ventilated room. Experiments were conducted to measure the initial velocity and the duration of a coughing burst. Computational fluid dynamics with a Eulerian—Lagrangian model was used to investigate the transport characteristics of evaporating droplets expelled into the ventilated room. The simulation results indicate that if expelled horizontally the droplets finally settle if their initial size is >100 μm, while if expelled upwards the droplets only settle if their initial size is ≥300 μm. Different ventilation set-ups vary in their ability to remove droplets produced by coughing. The mixing ventilation system has an almost equal efficiency for removing small passive droplets and the nuclei of droplets whose original size was 100 and 80 μm, respectively. For displacement ventilation, although it has high efficiency in removing small passive droplets, it has difficulty in removing the nuclei of large droplets. In the displacement system, small droplets show a two-zonal distribution in the room, but the nuclei of large droplets are subjected to gravitational force and tend to settle in the lower part of the room.

The performance of photovoltaic/thermal (PV/T) solar collector had been studied theoretically and experimentally for some years. Air and water streams were used as the heat carriers for space heating or services hot water systems. The cooling effect allows the PV module to work at lower temperature and its PV efficiency is therefore improved. However, such an advantage diminishes when the solar irradiance is high. To improve the situation a new type of PV/T collector is proposed. It works as the evaporator of a heat pump, in that refrigerant evaporates in the tubing at the back of the flat-plate collector and the PV module is adhered to the front surface. Mathematical models were developed to simulate the complex energy conversion processes. Numerical analysis was then performed based on the distributed parameters approach. An experimental rig was also built to test its real performance. Our results showed that the PV/T evaporator had an overall efficiency in the range of 0.64–0.87, thermal efficiency 0.53–0.64 and PV efficiency 0.124–0.135. The simulation results were found in good agreement with the experiment measurements. Copyright © 2006 John Wiley & Sons, Ltd.

The electrical conversion efficiency of the monocrystalline photovoltaic module is adversely affected due to the higher temperature of the solar cells. Therefore, cooling technologies to remove the excess heat generated by the photovoltaic modules play a vital role to enhance its output. In this article, thermal management of the conventional monocrystalline photovoltaic modules using phase change material has been experimentally evaluated. Phase change material with a melting point of 30°C to 32°C was encapsulated in the aluminium tubes that were 500 mm long having 19 mm inner diameter. Phase change material-filled tubes were attached to the rear side of the photovoltaic module at an equal distance to cover the module area of 0.30 m². The total mass of the phase change material used in the current experimental study was 1.0 kg. The average temperature of the modified photovoltaic module was 2.4°C to 2.8°C lower than conventional photovoltaic module during sunshine hours. The peak temperature of the conventional photovoltaic panel was lowered from 6°C to 9°C due to the inclusion of phase change material. The electrical conversion efficiency enhanced up to 2.0%. The current configuration of integrating phase change material with photovoltaic modules was observed advantageous as it assisted in enhancing the natural convection from the back of the photovoltaic module rather suppressing. An energy balance showing the trend of energy losses from conventional photovoltaic and photovoltaic with phase change material is also presented and discussed.