Constant Collection Temperature Research Articles

Annual overall energy and exergy analysis of N-PVT-CPC integrated VAR system: a constant collection temperature mode

This paper deals with detailed thermal modelling of N number of series-connected photovoltaic thermal-compound parabolic concentrator (N-PVT-CPC) collector integrated with lithium bromide-water (LiBr-H2O)-based single-effect vapour absorption refrigeration (VAR) system. The analysis of this novel integrated system has been carried out for constant collection temperature of the fluid that passes through the N-PVT-CPC collectors. The numerical simulations were performed on a typical clear day of May month for the climatic condition of New Delhi on MATLAB. From the present findings, it is concluded that the operation of the proposed system operating at To = 90°C is most suitable in respect of the higher duration of time and cooling effect and self-sustained up to six hours for a typical clear day of May month of New Delhi. Furthermore, a comparative analysis between N-PVT-CPC and N-PVT-FPC integrated VAR system has been presented on the basis of annual energy and exergy analysis.

Performance evaluation of a semi-transparent photovoltaic thermal (SPVT) inverted absorber flat plate collector (IAFPC) for constant collection temperature (CCT) mode

In the present communication an analytical model, to analyze the system performance of self-sustainable single-pass inverted conventional air collector integrated with semi-transparent photovoltaic thermal (SPVT) module has been developed. A comprehensive quasi-steady state performance analysis, based on the energy balance equation for each of the components (semi-transparent photovoltaic thermal (SPVT) module-partially covered, integrated with inverted air collector system for the operation at constant collection temperature (CCT) mode) has been studied. In the present study, an analytical modelling for exergy of the partially covered SPVT-IAFPC air collector system has been proposed and used for determining the performance at constant collection temperature (CCT) mode. Effect of the mass flow rate on the outlet temperature, electrical efficiency, cell temperature, rate of thermal efficiency has been studied and their thermal energy performance with overall exergy efficiency has been determined by developing a MATLAB program based on the analytical modelling. The inverted absorber semi-transparent photovoltaic thermal (SPVT) air collector has been analyzed for the following cases:1.Conventional inverted absorber FPC.2.Partially covered SPVT-IAFPC air collector.3.Fully covered SPVT-IAFPC-air collector.

Exergy analysis of N-photovoltaic thermal-compound parabolic concentrator (N-PVT-CPC) collector for constant collection temperature for vapor absorption refrigeration (VAR) system

In the present paper, the operating parameters of N-fully covered semitransparent photovoltaic thermal-compound parabolic concentrator (PVT-CPC) collector for constant collection temperature mode have been analyzed on the basis of an overall exergy analysis. The proposed system for a given design and climatic parameters will be applicable to the vapor absorption refrigeration system. The analyses are based on basic energy balance of each components, namely, solar cell, absorber plate, concentrator, flowing fluid, etc. Numerical computations have been carried out for New Delhi climatic condition by using MATLAB R2015a. The performance of the proposed system has also been compared with the performance of photovoltaic thermal-flat plate collector (PVT-FPC), conventional flat plate-compound parabolic concentrator (FPC-CPC) and conventional flat plate collector (FPC). Following conclusions have been made:(i)An overall exergy of N-fully covered semitransparent PVT-CPC system decreases with the increase in constant collection temperature,(ii)An overall thermal energy of N-fully covered semitransparent PVT-CPC system increases with the decrease in packing factor (βc) and.(iii)PVT-CPC and PVT-FPC with fully covered semitransparent are self-sustained collectors to be used for vapor absorption refrigeration system.The proposed system will be most appropriate for vapor absorption refrigeration (VAR) systems.

Exergy analysis of photovoltaic thermal (PVT) compound parabolic concentrator (CPC) for constant collection temperature mode

In this communication, an attempt has been made to evaluate exergy of photovoltaic thermal compound parabolic concentrator (PVT-CPC) water collector system [case (i)] for constant collection temperature mode of operation. The performance of PVT-CPC water collector systems can be analyzed in two modes namely (i) constant mass flow rate and (ii) constant collection temperature. In the present analysis, an analytical expression for mass flow rate and electrical efficiency of PV module for partially covered PVT-CPC water collector system [case (i)] have been developed to determined the performance under constant collection temperature mode. Such system will be most useful for thermal space heating of buildings to conserve fossil fuel to save environment. The comparison of proposed system with fully covered PVT-CPC water collectors [case (ii)], conventional CPC water collectors [case (iii)] and partially covered PVT water collectors [case (iv)] have also been carried out for climatic condition of New Delhi. Based on computation, it has been found that for fully covered PVT-CPC water collector system [case (ii)] (a) at high operating temperatures, instantaneous thermal efficiency has lower value in comparison with constant mass flow rate condition; (b) at high concentration ratio (C=5), higher operating temperature is achieved. The analytical expression of the electrical efficiency of the proposed system is also derived. An overall thermal and exergy analysis of PVT-CPC water collector system in terms of energy degraded into the environment and exergy destruction have also been carried out.

Energy matrices analyses of hybrid photovoltaic thermal (HPVT) water collector with different PV technology

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 0.66years on energy basis is obtained for c-Si and CIGS respectively, whereas on exergy basis maximum EPBT of 5.72years 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.

Energy and exergy analysis of hybrid photovoltaic thermal water collector for constant collection temperature mode

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.

Study of Hybrid Photovoltaic Thermal (HPVT) Solar Water Heater at Constant Collection Temperature for Indian Climatic Conditions

In this communication, two different cases, case A (collectors partially covered by PV modules; 30% PV) and case B (collectors fully covered by PV modules), connected in series have been considered for the study. The analysis has been based on the thermal energy, exergy, and electrical energy analysis. The whole study has been done by considering four weather conditions (a, b, c, and d types) for five different cities (New Delhi, Jodhpur, Bangalore, Mum- bai, and Srinagar) of India. Comparison of conventional flat- plate collectors (FPC) with case A and case B has also been done for New Delhi weather conditions. Based on numerical calculations, it has been found that the total annual gain is maximum for the Jodhpur city and minimum for the Srina- gar. The percentage variation between Jodhpur and Srinagar city is 25% and 23.4% for case A and case B, respectively. The annual gain for New Delhi, Mumbai, and Bangalore is nearly the same. The percentage variation between these three cities and Srinagar is 12%, 15.2%, and 10.4% for case A and 10.2%, 14%, and 9.3% for case B, respectively.

Exergy analysis of integrated photovoltaic thermal solar water heater under constant flow rate and constant collection temperature modes

In this communication, an analytical expression for the water temperature of an integrated photovoltaic thermal solar (IPVTS) water heater under constant flow rate hot water withdrawal has been obtained. Analysis is based on basic energy balance for hybrid flat plate collector and storage tank, respectively, in the terms of design and climatic parameters. Further, an analysis has also been extended for hot water withdrawal at constant collection temperature. Numerical computations have been carried out for the design and climatic parameters of the system used by Huang et al. [Huang BJ, Lin TH, Hung WC, Sun FS. Performance evaluation of solar photovoltaic/thermal systems. Sol Energy 2001; 70(5): 443–8]. It is observed that the daily overall thermal efficiency of IPVTS system increases with increase constant flow rate and decrease with increase of constant collection temperature. The exergy analysis of IPVTS system has also been carried out. It is further to be noted that the overall exergy and thermal efficiency of an integrated photovoltaic thermal solar system (IPVTS) is maximum at the hot water withdrawal flow rate of 0.006 kg/s. The hourly net electrical power available from the system has also been evaluated.

Transient analysis of collection-cum-storage water heater integrated with heat exchanger

Transient analyses of a collection-cum-storage water heater (i.e., built-in-storage/shallow solar pond) have been presented by incorporating the effect of a heat exchanger placed inside the system. Two modes of hot water withdrawal, viz. constant flow rate and constant collection temperature, have also been considered in the analysis. Numerical calculations have been made for typical days in Delhi, viz. 26 May 1978 and 10 March 1979. The effects of various parameters, viz. flow rate, constant collection temperature, movable insulation, heat capacity etc., on the water temperature and efficiency of the system have also been studied in detail.

Analysis of economical effect for compound configuration of solar collectors.

The compound configuration of a flat plate and a parabolic trough solar collector was considered on the basis of exergy (available work). The economical analysis was executed taking the heat collection temperature and the collector cost as parameteters. Two systems were treated in connection with the way in which the constant heat collection temperature was determined. One is the system in which it is determined by a factor other than the collector performance, such as the load demand. The other is the system in which it is determined by the collector performance, and is optimized by maximizing the yearly exergy output. As a result, the compound configuration produces only a slight increase in output. From an economical point of view, however, the former system can decrease the exergy cost by a maximum of over 50%, in which case the heat collection temperature is at the upper limit of the flat plate collector. On the other hand, the latter system can decrease the exergy cost by a maximum of about 10%. Therefore, it is concluded that the flexibillity in setting the heat collection temperature significantly decreases the effect of the compound configuration.

Influence of the thermal trap material on the performance of a roof as an inexpensive collector/storage system

An analysis of the behaviour of a network of pipes buried in a flat roof, with a thermal trap material at its top, is presented. An analytical solution for the heat flux entering a room and the heat retrieved for two modes of operation—(a) constant flow rate and (b) constant collection temperature, as functions of meteorological, as well as design, parameters—has been derived.

Thermal performance of “still-on-roof” as an inexpensive collection-cum-storage system

A straightforward analysis of a system that consists of a still and the roof of a building, along with a provision for withdrawal of hot water through pipes buried in the roof, has been presented. Withdrawal of hot water has been taken into account for two modes of operation, viz. (1) constant flow rate and (2) constant collection temperature. Some interesting conclusions have been drawn.

Effect of movable insulation on the performance of ground collector

This communication presents an analysis of the thermal performance of an inexpensive underground solar water heater. The system has been studied under two modes of heat collection (a) constant flow rate and (b) constant collection temperature. The effect of variation of different parameters, viz., flow rate of water, depth of plane of heat retrieval, thickness of flowing water column and duration of insulation on top to prevent night heat losses, has also been discussed.

Thermal Performance of ‘Still-on-Roof’ System with Water Flowing through the Roof

In the present communication, authors propose and analyze a system which consists of a solar still kept over the roof of a room, and a water-flowing arrangement in the roof. The performance of the system is studied under two modes of heat extraction, viz., constant flow rate, and constant collection temperature, An analytical model has been developed which provides explicit expressions for various performance parameters of the system. The model is useful in evaluating the system performance under the variation of different parameters. In order to appreciate the proposed configuration, numerical calculations are carried out corresponding to the typical climate of Delhi, India. The calculations show that the system is effective in reducing the heat flux entering the room and provides warm water in addition to the distilled water.

Transient analysis of closed loop solar water heating system

This paper presents a simplified transient analysis of a forced-circulation solar water heating system with a heat exchanger in the collector loop. Besides two modes of hot water withdrawal viz constant flow and constant collection temperature; the paper also studies the effectiveness of the flow through the heat exchanger and its length. The system performance has been further studied by considering different timings of starting hot water withdrawal. Calculations have been made for a typical cold day (26 January 1980) in New Delhi.

Transient analysis of forced circulation solar water heating system

This paper presents a transient analysis of a solar water heating system with forced circulation. Two modes of hot water retrieval have been taken into account viz direct from the tank and through a heat exchanger placed in the tank. Analysis has been presented both for constant flow and constant collection temperature modes. Effects of heat exchanger length and time of starting hot water retrieval on the system performance have also been studied. Numerical calculations have been made for a typical cold day (26 January, 1980) at Delhi.