Exergetic performance assessment of a solar photovoltaic thermal (PV/T) air collector

In this paper, an attempt is made to evaluate the exergetic performance of a solar photovoltaic thermal (PV/T) air collector. A detailed energy and exergy analysis is carried out to calculate the thermal and electrical parameters, exergy components and exergy efficiency of a typical PV/T air collector. Some corrections are done on related heat loss coefficients. An improved electrical model is used to estimate the electrical parameters of a PV/T air collector. Further, a modified equation for the exergy efficiency of a PV/T air collector is derived in terms of design and climatic parameters. A computer simulation program is also developed to calculate the thermal and electrical parameters of a PV/T air collector. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, parametric studies have been carried out. It is observed that the modified exergy efficiency obtained in this paper is in good agreement with the one given by the previous literature. It is also found that the thermal efficiency, electrical efficiency, overall energy efficiency and exergy efficiency of PV/T air collector is about 17.18%, 10.01%, 45% and 10.75% respectively for a sample climatic, operating and design parameters.     

水冷型PV/T系统的高效利用与发展现状

在光伏光热系统(PV/T)中为提高其电效率并高效利用低品位热能,近年来对于冷却工质及其工作方式的研究越来越多。其中,水冷式以其方便直接使用、无需二次换热、良好的光学特性和高热容量等优点,受到了广泛的理论研究和实验测试。通过以效率的视角探究光伏覆盖率、背管分布形式等影响流体冷却能力的因素,并结合相变PV/T、PV/T矩阵等PV/T未来发展新趋势,为今后水冷型PV/T系统进一步高效实验提供了研究方向。     

严寒地区PV/T-空气源热泵集成供热系统研究

严寒地区太阳能光伏光热(PV/T)技术应用于空气源热泵供暖系统,能实现低温环境下空气源热泵高效制热,最大限度提高可再生能源利用率。研究分析了空气源热泵供暖系统在严寒地区使用的局限性和普遍存在的问题;根据太阳辐射传热机理和空气传热介质的特点,研制出PV/T-空气源热泵集成供热系统,空气源热泵机组即使在室外空气温度-20℃时,其理论COP值也能达到5.37,提高了严寒地区空气源热泵的制热效率,为今后严寒地区供暖模式提供了一种新的思路。     

PV/T系统电热性能的实验研究

介绍了PV/T系统组成的原理,针对PV/T系统的电热性能进行了实验研究,并对实验数据进行了处理。计算出了不同参数下该PV/T系统的热效率和电效率,分析了这些参数对系统热效率的影响,以及PV/T模块表面温度对系统电效率的影响。     

Life cycle cost assessment of building integrated photovoltaic thermal (BIPVT) systems

The present paper deals with an analysis of the building integrated photovoltaic thermal (BIPVT) system fitted as rooftop of a building to generate electrical energy higher than that generated by a similar building integrated photovoltaic (BIPV) system and also to produce thermal energy for space heating. A thermodynamic model has been developed to determine energy, exergy and life cycle cost of the BIPVT system. The results indicate that although the mono-crystalline BIPVT system is more suitable for residential consumers from the viewpoint of the energy and exergy efficiencies, the amorphous silicon BIPVT system is found to be more economical. The energy and exergy efficiencies of the amorphous silicon BIPVT system are found to be 33.54% and 7.13% respectively under the composite climatic conditions prevailing at New Delhi. The cost of power generation is found to be US $ 0.1009 per kWh which is much closer to that of the conventional grid power.     

Exergetic performance assessment of solar photovoltaic cell (PV) assisted earth to air heat exchanger (EAHE) system for solar greenhouse cooling

An experimental system was developed and tested in order to investigate the exergetic performance of a solar photovoltaic system (PV) assisted earth-to-air heat exchanger (under ground air tunnel) that is used for greenhouse cooling at the Solar Energy Institute, Ege University, Izmir, Turkey. This system was under operational conditions successfully during the 2010 summer cooling season. This paper provides the experimental results obtained between 18th of August and 26th of August of in 2010. Exergy destruction in the system was calculated and presented in this paper using a reference temperature of 15 °C. Results are discussed and interpreted in the paper for various performance metrics, such as the effect of climatic conditions and operating conditions on the system performance. Results show that the system may be satisfactorily used for greenhouse cooling in the Mediterranean and Aegean regions of Turkey.     

Condenser heat recovery with a PV/T air heating collector to regenerate desiccant for reducing energy use of an air conditioning room

This paper presents an experimental test along with procedures to investigate the validity of a developed simulation model in predicting the dynamic performance of a condenser heat recovery with a photovoltaic/thermal (PV/T) air heating collector to regenerate desiccant for reducing energy use of an air conditioning room under the prevailing meteorological conditions in tropical climates. The system consists of five main parts; namely, living space, desiccant dehumidification and regeneration unit, air conditioning system, PV/T collector, and air mixing unit. The comparisons between the experimental results and the simulated results using the same meteorological data of the experiment show that the prediction results simulated by the model agree satisfactorily with those observed from the experiments. The thermal energy generated by the system can produce warm dry air as high as 53 °C and 23% relative humidity. Additionally, electricity of about 6% of the daily total solar radiation can be obtained from the PV/T collector in the system. Moreover, the use of a hybrid PV/T air heater, incorporated with the heat recovered from the condenser to regenerate the desiccant for dehumidification, can save the energy use of the air conditioning system by approximately 18%.