• Energy Research

Abstract This article describes the typical expression for the wholly exposed area of PVT-CPC Collectors built-in double slope solar still matching with the Hottel-Whillier-Bliss expression for (FPC). The drawbacks in the partly exposed area of photovoltaic thermal collectors namely high manufacturing cost, servicing cost is more and Low thermal movements of molecules owing top loss. The above drawbacks of partly exposed area of PVT-CPC (for N-identical numbers) have been completely discussed in wholly exposed area of PVT combined with CPC collector for the same value of watt peak. The typical expression for the different parts of PVT-CPC built-in with double slope solar still has also been development. The mathematical term for our current work is also compared with cases: (1) PVT flat plate collector double slope solar unit (2) Flat plate collector included with double slope solar still (conventional) and (3) Double slope distiller unit (passive). The instant efficiency of proposed work is found to be better than case (1) , (3) but a little less than the case (2) .

Abstract In this paper, an attempt has been made to evaluate and compare the energy matrices of a hybrid photovoltaic thermal (HPVT) water collector under constant collection temperature mode with five different types of PV modules namely c-Si, p-Si, a-Si (thin film), CdTe and CIGS. The analysis is based on overall thermal energy and exergy outputs from HPVT water collector. The temperature dependent electrical efficiency has also been calculated under composite climate of New Delhi, India. It is observed that c-Si PV module is best alternative for production of electrical power. Maximum annual overall thermal energy and exergy is obtained for c-Si PV module. The maximum and minimum EPBT of 1.01 and 0.66 years on energy basis is obtained for c-Si and CIGS respectively, whereas on exergy basis maximum EPBT of 5.72 years is obtained for a-Si and minimum of 3.44 in obtained for CIGS PV module. EPF and LCCE increase with increasing the life time of the system.

This paper deals with the analysis of hybrid photovoltaic thermal (PVT) water collectors under constant collection temperature mode unlike constant flow rate mode. The analysis has been carried out in terms of thermal energy, electrical energy and exergy gain for two different configurations namely case A (collector partially covered by PV module) and case B (collector fully covered by PV module). The results are compared with the conventional flat plate collector (FPC). The effect of collector area covered by PV module on the performance of hybrid PVT water collector has been studied. The characteristic equations have also been developed for both the cases. It has been observed that case A is more favorable for thermal energy point of view, while case B is suitable for electricity generation. On the basis of the numerical calculations the annual thermal energy gain is found to be 4167.3 and 1023.7 and annual net electrical energy gain is 320.65 and 1377.63 for cases A and B respectively. The annual overall thermal energy gain is decreased by 9.48% and an annual overall exergy gain is increased by 39.16% from case A to case B.

Abstract This paper deals with the development of analytical characteristic equation for N identical fully covered photovoltaic thermal (PVT) compound parabolic concentrator collector (CPC) integrated solar distillation system which is similar to Hottel-Whillier-Bliss equation of flat plate collector (FPC). The partially covered PVT has disadvantages like (a) thermal performance is lower due to higher top loss coefficient, (b) maintenance is higher and (c) fabrication is expensive. These problems are fully addressed in the case of fully covered PVT for the same watt peak. The development of analytical characteristic equation for the proposed system consists of writing energy balance equations for its various components. The results of proposed N-PVT-CPC integrated active solar distillation system [case (i)] has been compared with fully covered N identical PVT-FPC integrated solar distillation system [case (ii)] and conventional N identical FPC active solar distillation system [case (iii)]. It has been observed that average instantaneous efficiency of case (i) is higher than case (ii) by 10.60%, but lower than case (iii) by 20.74%.

Abstract This paper deals with the detailed analysis of evacuated tubular collector (ETC) connected in series in the terms of thermal energy and exergy gain. The study have been done by considering four type of weather conditions (a, b, c and d type) for the climatic condition of New Delhi, India. The maximum outlet temperature increases from 53.91 °C to 129.23 °C and the useful daily thermal gain increases from 3.29 kW h to 6.34 kW h for as the number of collector increases from two to six, at constant mass flow rate ( m f ) = 0.002 kg/s. For a mass flow rate ( m f ) = 0.002 kg/s, the temperature difference between inlet and outlet ( Δ T ) increases (55.52–133.29 °C) as the number of collector increases from 2 to 12 and then becomes almost constant. Monthly gain in thermal energy and exergy are also evaluated by considering four number of collectors connected in series and at constant mass flow rate of 0.002 kg/s. The characteristic equations of ETC have also been developed. Instantaneous thermal efficiency decreases from 53.5% to 34.4% as the number of ETC increases from two to six.

Abstract In present communication, an experimental study has been carried out to evaluate the performance of series connected photovoltaic thermal (PVT) water collector in terms of overall thermal energy gain and overall exergy gain. Earlier developed theoretical model has been validated by performing the experiment in a clear sky day, hazy day and partially cloudy day for New Delhi climatic condition. It was found that theoretical results were in good agreement with experimental results. The annual energy gain, exergy gains, CO2 mitigation, energy matrices and carbon credit of the system have also been discussed. The energy pay-back time was found to be 1.50 and 14.19 years on overall thermal energy and exergy basis respectively. Carbon credits earned in a year were Rs. 6321.70 for overall thermal energy gain and Rs. 667.30 for overall exergy gain. For 30 years of life time, cost of one unit of electricity was estimated to be Rs. 1.53 on overall thermal energy basis however it was Rs. 14.45 on overall exergy basis.

Abstract In this communication, an attempt has been made to develop modified Hottel-Whillier-Bliss (HWB) equation for N-number of fully covered photovoltaic thermal- compound parabolic concentrator (N-PVT-CPC) collector. The Analysis is based on basic energy balance equations for each component of the system as a function of design and climatic parameters. Developed modified Hottel-Whillier-Bliss (HWB) equation is applicable for various configurations namely conventional flat plate-compound parabolic concentrator (FPC-CPC), fully covered photovoltaic thermal-flat plate collectors (PVT-FPC) and conventional flat plate collectors (FPC) as a special case. The characteristic curve for thermal and electrical efficiency has also been developed for all cases considered in the present paper. Further, an experimental validation for N = 1 has also been carried out under indoor simulation condition.

Renewable energy (RE) resources have enormous potential and can meet the present world energy demand by using the locally available RE resources. One of the most promising RE technologies is photovoltaic (PV) technology. This paper presents a review of the available literature covering the various types of up and coming PV modules based on generation of solar cell and their applications in terms of electrical as well thermal outputs. The review covers detailed description and thermal model of PV and hybrid photovoltaic thermal (HPVT) systems, using water and air as the working fluid. Numerical model analysis and qualitative evaluation of thermal and electrical output in terms of an overall thermal energy and exergy has been carried out. Based on the thorough review, it is clear that PVT modules are very promising devices and there exists a lot of scope to further improve their performances particularly if integrated to roof top. Appropriate recommendations are made which will aid PVT systems to improve their overall thermal and electrical efficiency and reducing their cost, making them more competitive in the present market.

In this paper, the energy balance equations for the different components of hybrid photovoltaic thermal integrated-biogas plant have been written for quasi-steady state conditions to develop a thermal model. An analytical expression for slurry temperature has been obtained as a function of design and climatic parameters namely mass of the slurry, mass flow rate of fluid in collector, number of collectors, solar intensity, ambient temperature etc. Numerical computations have been carried out for climatic conditions of Srinagar, India. Based on mathematical computations it has been observed that the optimum slurry temperature (∼37°C) is achieved for a given set of design parameters of biogas plant and hybrid collectors (MS = 2000, \(\dot m_f = 0.05 kg/s\), L = 25 m). It is also observed that the peak slurry temperature decreases with increase in mass of the slurry as expected. Equivalent CO2 credits earned by hybrid biogas plant for optimised parameters have also been evaluated.