Flat Plate Solar Collector System Research Articles

Fabrication and Performance Evaluation of Integrated Solar-Driven Membrane Distillation System with Serpentine-shape of Flat Plate Solar Collector for Seawater Desalination

Solar-powered membrane distillation (SPMD) system has gained its popularity in desalination application for past decade credit to the system efficiency in producing pure water and the utilization of renewable energy. However, most of the past SPMD works used commercial solar thermal collector (STC) as the thermal energy supply to the feed solution and the study only focused on the performance of the system in terms of flux and salt rejection. In this work, a self-made flat plate solar collector (FPSC) with the serpentine-shape pipe was designed and fabricated to study the effect of the STC towards the membrane performance. Before testing, a simulation work of the fluid flow inside the serpentine-shape pipe of the FPSC was analyzed using NX 10.0 computer-aided design simulation. After that, the efficiency of the self-made FPSC system was tested directly to sunlight in order to identify the maximum irradiance and the temperature of the feed solution. Due to the fluctuation of solar irradiance, the experimental setup of the SPMD system was tested using a solar simulator, and the performance was compared with the membrane distillation (MD) system without integration with FPSC system. Based on the simulation data, it can be concluded that the heat losses across the pipe are due to the slower fluid velocity and sudden pressure drop, which attributed to centripetal force and pressure differences. Meanwhile, the outdoor evaluation data showed that the temperatures of collector and water inside the feed tank could reach up to 84°C and 64°C, respectively when the maximum irradiance of 938 W/m2 was applied. For the performance evaluation between with and without the self-made FPSC system, it can be seen that only marginal difference can be observed for the permeate flux and salt rejection with an average difference of 6.06% and 1.29%, respectively.

Study on the hysteresis characteristic of solar thermal storage system

The thermal storage efficiency is one of the important indicators for evaluating the operation of solar thermal storage system. Affected by the thermal inertia of the system, the analysis of the relationship between the thermal storage efficiency and solar radiation, which is inadequate at the smaller time scale. This paper measured the operation of a flat plate solar collector system, studied the hysteresis characteristics of the system’s collector efficiency changes with solar radiation, took a numerical solution method for the actual lag time of the system and finally obtained the actual influence rule of solar radiation on the collection efficiency per minute. The results show that the solar collector’s efficiency change lags behind the solar radiation by 27 min; combined the lag time, the relationship between the modified thermal storage efficiency and solar radiation also were analysed; initially the modified storage efficiency per minute increases with the solar radiation, then gradually decrease after reach a certain value, due to the overall system temperature is higher and the system temperature rise is smaller when the solar radiation is large enough; the varying curve conforms to quadratic function. It provides theoretical support and practical reference for contrasting and evaluating the thermal storage efficiency changes with solar radiation in a smaller time scale.

Study on the PCM flat-plate solar collector system with antifreeze characteristics

This paper proposes a flat-plate solar collector system (FPSCs) with antifreeze characteristics which uses the phase change material (PCM) to store up a moderate amount of thermal energy during the daytime and release the energy during the night to prevent the FPSCs from freezing damage. Previous studies about the FPSCs exploiting the PCM are mainly focus on the purpose of balancing the tank water temperature between the daytime and night. In the present work, the study on the characteristics of the PCM-FPSCs for the purpose of antifreeze has been conducted. A mathematical model with high precision for the daytime working and night freezing of the system is present. The daytime working and night antifreeze performance of the system are evaluated. The results show that the conventional FPSC system will get frozen when the daily average temperature is less than 5 °C. The PA-FPSC system can work when the daily average temperature is in the range of 0–5 °C.

Numerical study of the effect of nanoparticles on thermoeconomic improvement of a solar flat plate collector

The influence of the nanoparticle Al2O3 on the thermo-economic optimization of a solar flat plate collector system at different mass flow rates of the working fluid is studied. In particular, the effects of the nanoparticle on the simultaneous optimization of the total annual cost (TAC) and the collector efficiency are investigated. In order to perform multi-objective optimization with the TAC and efficiency as the two objective functions with seven decision variables, including various collector design parameters, mass flow rate and the nanoparticls volumetric concentration, a Particle Swarm Optimization algorithm (PSO) is used. The sensitivity of the various design parameters on the collector efficiency is determined and investigated. Analysis of results reveal that the Pareto front for the case with a mass flow rate of 0.2kg/s dominates over the case with a mass flow rate of, and the differences are found to become more pronounced with the addition of the nanoparticle, especially at higher efficiencies. It is also observed that the collector system efficiency increases further with the nanoparticle concentration. It is found that for the optimal performance of the system that simultaneously optimizes TAC and efficiency, all the collector design parameters, except for the number of tubes, can be selected at lower magnitudes when the nanoparticle additive is introduced into the working fluid. Overall, parameter optimization with the use of nanoparticle results in a decreases in the TAC and increase in the efficiency of the flat plate collector.

Thermal-hydraulic characteristics and exergy performance in tube-on-sheet flat plate solar collectors: Effects of nanofluids and mixed convection

Flat plate solar collector (FPSC) is one of the most popular equipment among solar energy systems which can be utilized for heating of domestic or public buildings where the demands for hot water are quite indispensable. Although they have a number of benefits such as no need for sun tracking and low maintenance cost, their low thermal performance is considered as a hindrance in their extensive development. In this paper, a three-dimensional inclined tube-on-sheet flat plate solar collector is numerically modeled. The FPSC system is deemed to work under conjugated laminar mixed convection heat transfer mechanism while the operational fluid is selected to be Al2O3/water nanofluid. The influence of several parameters on the performance of the present FPSC, namely inlet alumina/water nanofluid temperature, and volume concentration, heat flux absorbed by the absorber plate, dimensionless numbers consist of Reynolds (Re), Grashof (Gr), Prandtl (Pr), and Richardson (Ri) are discussed on the heat transfer, fluid flow, and entropy generation. Furthermore, the effects of friction factor inside the riser as well as the pressure drop are taken into the account in this research. Results revealed that increasing the volume fraction of nanofluid at a fixed Reynolds number declines the outlet temperature whereas lowering the Reynolds number at a same volume fraction gives rise to higher outlet temperature. From heat transfer standpoint, it is observed that in a constant Reynolds number by increasing nanoparticle volume fraction, the Nusselt number falls while the heat transfer coefficient rises. In addition, rising the Reynolds number eventuates in friction factor reduction while the pressure drop augments. Moreover, from the obtained outcomes, it is figured out that generally using alumina/water nanofluid provides lower total entropy generation, in comparison with the water. Simulation data reveal that alteration in the heat flux does not have any sensible effects on the friction factor.

Performance Analysis of Three Fluid Heat Exchanger Used in Solar Flat Plate Collector System

Abstract In the present study, the thermal performance of a three fluid heat exchanger (TFHE) used in solar flat plate collector system is studied. The TFHE is an improved version of double pipe heat exchanger, where a helical tube is inserted between two concentric straight tubes for better performance. This paper presents a new technique of simultaneous air and water heating in TFHE using solar energy. The heating cost can be minimised considerably by supplying the hot water or thermal fluid from a solar flat plate collector through the helical tube of TFHE to heat incoming cold air and water in the inner most pipe and outer annulus. The TFHE is investigated experimentally and validated by comparing the result of experimental approach with literature. Decent agreements between the experimental and literature values are observed. The purpose of this study is to determine the effect of Reynolds number and Dean number on performance of the TFHE in steady-state for both flow configurations. The overall heat transfer coefficients, U o,h-n varies directly and effectiveness, ɛ h-n varies inversely with hot water volume flow rate, however hot water flow rate have least or no effect on coil side Nusselt number, Nu h . The effect of inner Dean Numbers on overall heat transfer coefficients, U o,h-n and effectiveness, ɛ h-n is negligible in parallel flow configuration, however is appreciable in counter flow configuration.ommittee of RAAR 2016.

기상조건과 축열조 용량에 따른 평판형 태양열 집열기 시스템의 동적 성능 해석

기상조건과 축열조 용량에 따른 평판형 태양열 집열기 시스템의 동적 성능 해석

평판형 태양열 집열기의 연중 열적 성능의 모델링 해석

Abstract >> The monthly-average meteorological data, in particular, the monthly average daily terrestrial horizontal insolation are required for designing solar thermal energy systems. In this paper, the dynamic thermal performanceof a flat plate solar collector system is numerically investigated through a year from the monthly average insolationdata in Seoul. For a specified data set of solar collector system, the dynamic behaviors of total solar radiationon the tilted collector surfaces, heat loss from the collector system, useful energy and collector efficiency are analyzed from January to December by a mathematical simulation model. In addition, the monthly average daily total solar radiation, useful energy, and daily collector efficiencies through a year are estimated. The simulatedresults show that the average total radiation is highest in March and the useful energy is highest in October, whilethe total radiation and the collector efficiency are lowest in July. Key words :

Experimental Study of Solar Hot Water System Design

This paper investigates the design of flat-plate solar collector system experimentally.The production amount of hot water depends on the type and size of the system, the amount of sun rays available at the site, proper installation, and the tilt angle and orientation of the collectors with respect to the south direction. The results show that the amount of the energy collected by the thermal fluid and the absorber plate are inversely proportional to that thickness and diameter of both riser and drum tubes, and it decreases when the air gab between glasses layer increases( prevents the sun rays and the solar effect ).The intensity of the mean sun rays daily per hour is an important factor to the energy absorbed by the collector. This study used aluminumas an absorber plate because its thermal conductivity is high more than copper and mild steel ,its price is cheap.

Optimal control of flow in solar collector systems with fully mixed water storage tanks

The paper deals with optimal flow control in closed loop flat plate solar collector systems. The water storage tank operates in the fully mixed regime. Two design configurations were considered: (A) one serpentine in the tank (for the secondary circuit) and (B) two serpentines in the tank (for both primary and secondary circuits). An indirect optimal control technique based on Pontryagin’s maximum principle was implemented. A detailed collector model and realistic meteorological data from both cold and warm seasons were used in applications. Configuration (A) gives better performance than configuration (B) but cannot be used during the cold season at higher geographical latitudes. The optimal operation strategy involves two step up and down jumps between zero and a maximum allowable fluid flow rate in the primary circuit. During days with overcast sky, the pump in the primary circuit operates almost continuously. During days with cloudy or clear sky, the pump often stops. Heat provided to the user increases when the maximum fluid flow rate increases. This applies to both configurations (A) and (B). In the case of configuration (B), the heat provided to the user becomes rather constant at higher flow rates. When a constant flow rate strategy is adopted, there is an optimum ratio between the volume of the storage tank and the area of the solar energy collection surface: V s/ A ≈ 33.3 L/m 2. The optimal control strategy does not exhibit such an optimum: the thermal energy supply to the user (slightly) decreases by increasing the ratio V s/ A.

Optimal control of flow in solar collectors for maximum exergy extraction

The best operation strategies for open loop flat-plate solar collector systems are considered. A direct optimal control method (the TOMP algorithm) is implemented. A detailed collector model and realistic meteorological data from both cold and warm seasons are used in applications. The maximum exergetic efficiency is low (usually less than 3%), in good agreement with experimental measurements reported in literature. The optimum mass-flow rate increases near sunrise and sunset and by increasing the fluid inlet temperature. The optimum mass-flow rate is well correlated with global solar irradiance during the warm season. Also, operation at a properly defined constant mass-flow rate may be close to the optimal operation.

Optimization of operational and design parameters of plane reflector-tilted flat plate solar collector systems

Optimization of operational and design parameters of plane reflector-tilted flat plate solar collector systems

Optimization of operational and design parameters of plane reflector-tilted flat plate solar collector systems

Due to the increased interest in the utilization of solar energy, it is essential to enhance the energy collection of solar energy devices. In this paper, a theoretical analysis of the instantaneous, daily, and yearly enhancement in solar energy collection of a tilted flat-plate solar collector augmented by a plane reflector is developed. The shadow effect due to the reflector on the collector is considered in the analysis. A FORTRAN computer program has been constructed based on the analysis in order to study the effect of different operational and design parameters of plane reflector-tilted flat-plate solar collector system on the collector solar energy collection. These parameters include collector-reflector system orientation and tilt angles, collector elongation ratio, and reflector overhang ratio.

Performance of a second generation solar cooling unit

This paper describes the performance of a 1.5 ton solar-operated absorption refrigeration unit operating with a 14 m 2 flat-plate solar collector system and containing five heat exchangers: the generator, the absorber, the condenser, the solution heat exchanger (all of these being of shell-and-tube type) and finally the evaporator, which is of the fin-and-tube type. One circulation pump is used for solution flow and another for the hot water flow. The condenser and the absorber are both cooled by city mains water. This particular unit, called the second generation unit, is compared with an earlier, first-generation unit (FGU), i.e. a low-cost, locally manufactured unit of 0.5 ton capacity. The results are based on the observed operation of the unit during hours of sufficient solar irradiance in April and May, the beginning of the air-conditioning season in Jordan. The variation of both the generator and evaporator temperatures during the test period are reported. Also reported is the performance of the unit as measured by the actual and theoretical (ideal) coefficients of performance, both of these being functions of the temperatures and solar irradiance. The maximum values obtained for both actual and theoretical coefficients of performance were 0.75 and 2.7 respectively. These values are within the range of values published in literature, and higher than those obtained by the FGU.

Analysis of Boiling Flat-Plate Collectors

A detailed model for use with TRNSYS, capable of modelling a wide range of boiling collector types, was used to analyze boiling flat-plate collector systems. This model can account for a subcooled liquid entering the collector, heat losses in the vapor and the liquid return line, pressure drops due to friction in the collector and piping, and pressure drops due to the hydrostatic head of the fluid. The model has been used to determine the yearly performance of boiling flat-plate solar collector systems. A simplified approach was also developed which can be used with the f-Chart method to predict yearly performance of boiling flat-plate collector systems.

Degraded aqueous glycol solutions: pH values and the effects of common ions on suppressing pH decreases

Aqueous solutions of ethylene glycol and propylene glycol are used as heat transfer liquids in flat-plate solar collector systems. Both of the glycols are susceptible to thermal oxidative reactions, which produce organic acids with a resulting decrease in pH of the solutions. The effects of temperature, metals, common ions and oxidation conditions (aeration/deaeration) on the thermal stability of the glycol solutions were evaluated based on measuring changes in pH. Aerated heated glycol solutions produced acidic solutions within 3360 h (140 d) of testing, when in contact with either metallic aluminum or copper. Common ions (anions of the acid degradation products) were effective in suppressing decreases in pH, especially when aluminum was present.

Cost per million BTU of solar heat, insulation, and conventional fuels

The cost per million BTU is calculated for insulation (useful heat saved) and for flat plate solar collector systems applied to space heating of houses and to water heating. Results are compared with cost per million BTU from conventional sources.

The determination of acidic degradation products in aqueous ethylene glycol and propylene glycol solutions using ion chromatography

Aqueous ethylene glycol and propylene glycol solutions are the principal antifreezes used as heat transfer fluids in flat-plate solar collector systems. Acidic degradation produces formed in the thermal oxidation of these solutions have been analyzed using ion chromatography (IC) and the ion-chromatography exclusion (ICE) method of analysis. The primary acidic degradation product found in the case of ethylene glycol solutions was glycolic acid. Propylene glycol solutions yielded mainly lactic acid. The presence of metallic copper significantly increased the amount of degradation products over that produced in the absence of metal. Solutions heated in the presnce of metallic aluminum were only slightly more degraded than those heated without metal, but contained relatively large amounts of formic acid. Only traces of formic acid were observed when the glycol solutions were heated in the absence of metal or in the presence of metallic copper.

Economic Feasibility of Retrofit Solar Hot Water Systems

This paper presents the results of an economic feasibility study of 177 public buildings (schools, hospitals, local government buildings, and public care facilities) in the Commonwealth of Virginia to determine if active flat-plate solar collector systems could economically augment or replace existing hot water heating installations. Utilizing the F-CHART method and life-cycle costing techniques, two collector areas were determined for each facility: the optimum collector area (where the present worth of the lifetime net savings was maximized) and the maximum collector area (where the amount of solar energy that could be utilized without losing money was maximized). Solar systems that would pay for themselves within 25 years could be installed in 77 of the 177 buildings (43.5%), with a mean discounted payback period of 17.7 yr. These units would provide 78.8% of the facilities' hot water loads. The study also reveals that for a given fuel cost, the collector areas of these systems are directly proportional to the total hot water loads. In addition, the shortest discounted payback period of an optimally designed solar system may be obtained directly from the fuel cost. These relationships could lead to simplified sizing techniques for active solar hot water system retrofits.

Net energy analyses of eight technologies to provide domestic hot water heat

Net energy analyses have been carried out for eight trajectories which convert an energy source into heated domestic water. In addition, economic and metals consumed estimates have been made for three methods of producing heated domestic water. While some of the trajectories producing electrically heated water showed a slightly higher ratio of energy produced to energy consumed than a flat plate solar collector system, when all factors were considered (i.e. cost, quality of energy, and metals consumed), the flat plate solar collector system appears to be the system our energy policy should encourage for heating domestic water, even in the cloudy inter-Lakes area of the United States. Based on only net energy factors, it seems clear that the synthetic fuels program should not be encouraged as a means of providing a fuel source for heating domestic water.