Double-pass Air Collector Research Articles

Photovoltaic thermal solar air heater under external recycle: A performance study

ABSTRACT The photovoltaic thermal (PV/T) systems are promising techniques for cooling photovoltaic modules and performance improvement. The heat-exchanging fluid removes the heat from the PV module, which can be utilized in the low-temperature application, including space heating. In the present study, a photovoltaic thermal system based on a double pass air collector under recycling is theoretically investigated for its overall performance and analysis. An analytical model explaining the different temperatures and heat transfer characteristics of the proposed PV/T system is developed and employed to study the effects of different recycling ratios at varying mass flow rates, the area covered by the PV module (packing factor), solar irradiation, and varying duct depth on thermal, electrical, and combined efficiency. The analytical model utilizes an iterative solution to work out the governing energy balance equations describing the complex heat and mass exchanges. The results show that the new design collector encloses photovoltaic cells under recycling, reduces the PV surface temperature from 97°C (without cooling) to 45°C (with cooling) at 0.15 kg/sec mass flow rate of air and recycle ratio of 1.8 and, thereby improves the electrical efficiency from 12% to 16%, which is 13% more increment than a non-recycling case. The influences of the identified parameters, which may vary with the proposed design performance, are presented in detail.

MATHEMATICAL MODELLING AND PERFORMANCE ANALYSIS OF DIFFERENT SOLAR AIR COLLECTORS

The purpose of using solar air collectors is to raise the atmospheric air temperature to a temperature which can be used for various low and medium temperature applications. Collector, absorber and airflow arrangement are the most important components in the solar air collector. The performance of the collector depends on its heat loss and the absorber area that is in contact with the airflow. This study involves the theoretical simulation of the effect of mass flow rate on the performance, for flat plate and v-groove collectors that are in single and double pass configurations. Results show that the v-groove double pass air collector has the highest efficiency value of 56% at . The performance is greater than flat plate double pass collector, which has an efficiency of 54% under the same operating conditions. KEYWORDS: solar air collector; flat plate collector (fpc); v-groove collector; efficiency; single pass; double pass

Performance analysis of a hybrid photovoltaic thermal double pass air collector using ANN

This paper presents the use of artificial neural network for performance analysis of a semi transparent hybrid photovoltaic thermal double pass air collector for four weather conditions (a, b, c and d type) of New Delhi. The MATLAB 7.1 neural networks toolbox has been used for defining and training of ANN for calculations of thermal energy, electrical energy, overall thermal energy and overall exergy. The ANN model uses ambient air temperature, global solar radiation, diffuse radiation and number of clear days as input parameters for four weather conditions. The transfer function, neural network configuration and learning parameters have been selected based on highest convergence during training and testing of network. About 2000 sets of data from four weather stations (Bangalore, Mumbai, Srinagar, and Jodhpur) have been given as input for training and data of the fifth weather station (New Delhi) has been used for testing purpose. It has been observed that the best transfer function for a given configuration is logsig. The feedforward back-propagation algorithm has been used in this analysis. Further the results of ANN model have been compared with analytical values on the basis of root mean square error.

Energy and exergy analysis of a hybrid photovoltaic thermal double pass air collector

In this paper an attempt has been made to analyze the performance of semi transparent hybrid PVT double pass air collector. Based on the first law of thermodynamics, energy balance equations are for-mulated to derive the analytical expression for air temperature at the outlet, as a function of the design and climatic parameters for investigating the performance of semi transparent hybrid PVT air collector. The analysis is based on quasi-steady state condition. This paper shows the detailed analysis of energy and exergy of a semi transparent hybrid PVT double pass air collector and its comparison with single pass air collector for four weather conditions (a, b, c and d type) for five different cities (New Delhi, Bangalore, Mumbai, Srinagar, and Jodhpur) of India. It has been analyzed that if such systems are installed only at 10% of the total residential houses in Delhi, then the total carbon credits earned by the system is found to be Rs. 1767 millions in terms of thermal energy and Rs. 493 millions in terms of exergy for double pass air collector whereas Rs. 1528 millions in terms of thermal energy and Rs. 446 millions in terms of exergy for single pass air collector. The results clearly shows that hybrid PVT double pass air collector have better performance as compared to single pass air collector.