Experimental Study On The Influence Of Indoor Air Organization On The Thermal And Power Generation Performance Of PV Window

In China,building energy consumption accounts for about 33% of the total energy consumption of society,among which the building cooling and heating energy consumption caused by heat transfer of external window accounted for 25% to 40% of the total building energy consumption.Thus,energy-efficient windows has become one of the key links of energy-saving,emission-reduction and green buildings in China.As a kind of renewable energy,solar energy is favored by its large reserves,non-pollution and high performance.The use of solar energy has become the focus of research.Solar photovoltaic window(PV-W),as an important application form of photovoltaic building integration(BIPV),can not only make use of the photoelectric effect to generate electricity,but also greatly reduce the heat gain of solar radiation through the external window.It is considered to be one of the effective ways to realize the active energy saving.The thermal and power properties of PV-W is affected by its internal and external environment.At present,there are many researches on the influence of the external environment of the building,but the research on the the internal environment,including the influence of the indoor air organization on the performance of the PV-W,has not been published.Therefore,from the perspective of the internal environmental impact of the building,an experimental platform of PV-W was established to study its thermal and power properties in the Taiyuan region.In summer,the influence of indoor air temperature and air supply velocity of mixing ventilation(MV)system and displacement ventilation(DV)system on the thermal and power performance of a-Si single layer PV-W were studied.In addition,the thermal and power properties of a-Si double layer PV-W under the DV system were tested and compared.The main conclusions of this paper are as follows:(1)With the decrease of indoor air temperature,the power performance of PV window is gradually increased,but the heat transfer through the PV-W is also increasing under summer conditions.When the indoor temperature reduces from 26? to 20?,the DC output power is increased by 6.7% and the heat gain of PV-W is increase by 14.5% under MV system;while the DC output power is increased by 2.3% and the heat gain is increase by 17.2% under MV system.(2)The increase of air supply velocity improves the power performance of PV-W,but its influence is relatively smaller than the indoor air temperature.When the air velocity is increased from 2m/s to 3m/s,the DC output power of the PV-W is increased by 2.1% and 1.2% under the MV and DV systems respectively.The influence of air supply velocity on the thermal performance of PV-W is more complicated.Under the experimental conditions,with the increase of the air velocity,the heat gain of PV-W increases firstly and then decreases.And the 2.6m/s air supply velocity under the two kinds of systems caused the highest heat gain of PV-W.(3)Compared with the MV system,under the premise of the same air conditioning energy consumption,the DV system is more conducive to improve the thermoelectric performance.When the indoor air temperature is set at 20?,the air velocity is set at 3m/s,compared with the MV system,the inner surface temperature of PV-W decreased by 20.3%,the power generation increased by 10.5%,and the heat gain of PV-W reduced by about 37.4% under the DV system.(4)In summer cooling operation mode,when the indoor air temperature is set at 22? and 24? under MV system,the thermal environment of work area(0.1m?Z?1.1m)can basically meet the thermal comfort.However,due to the experimental conditions,the height of the human head position(Z=1.1m)in the work area has obvious air blowing because of the high air supply velocity.Owing to the characteristics of air flow organization of DV system,there is a phenomenon of high air velocity in the human foot position(Z=0.1m)in the summer cooling and winter heating modes.Moreover,due to the role of buoyant plume,the temperature difference between the head and foot of the working area is more than 2?,it may cause thermal comfort problems that should be noted in the design.