scholarly journals EXPERIMENTAL INVESTIGATION OF ENERGY CHARACTERISTICS OF EVACUATED TUBE HEAT-PIPE SOLAR COLLECTOR SYSTEM

2015 ◽  
Author(s):  
Antanas KAVOLYNAS ◽  
Rolandas DREJERIS
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Flow Rate ◽  
Solar Collector ◽  
Storage Tank ◽  
Hot Water ◽  
Heat Transfer Agent ◽  
Energy Characteristics ◽  
Collector System ◽  
Evacuated Tube

Evacuated tube heat-pipe solar collector system with closed heat pipe has been experimentally investigated. Experiments have been fulfilled using the solar imitator whose energy irradiance on the surface of the solar collector at the constant ambient conditions is 800 W/m². Energy characteristics of the solar collector system with different flow-rates of the heat-transfer agent have been investigated using various flow-rate speeds of the heat-transfer agent. It has been stated that the increase of the flow-rate of the heat-transfer agent in the system from 0.01 to 0.12 kg/s would minimize the average collector efficiency from 0.81 to 0.55. When the reduced flow-rate of the heat-transfer agent has been used in the system, the higher temperature of the hot water is reached in the storage tank and at the same time the temperature of the heat-transfer agent in the system is increased. Thus, more energy has been lost in the pipeline and hot water storage tank, but less energy is used for the circulation of the heat-transfer agent energy. Increasing the agent flow-rate speed in the system has reduced the heat losses in the pipeline, but more energy is used for the energy circulation of the heat-transfer agent. Therefore, the medium efficiency of the solar collector system has changed insignificantly (0.47 ± 0.01).

scholarly journals Thermal Characteristics Analysis on Multi- Heat Pipe Induced Heat Exchanger

2019 ◽  
Vol 9 (2S2) ◽  
pp. 143-147 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Hot Water ◽  
Working Fluid ◽  
Physical Parameters

In this investigation of multi heat pipe induced in heat exchanger shows the developments in heat transfer is to improve the efficiency of heat exchangers. Water is used as a heat transfer fluid and acetone is used as a working fluid. Rotameter is set to measure the flow rate of cold water and hot water. To maintain the parameter as experimental setup. Then set the mass flow rate of hot water as 40 LPH, 60LPH, 80 LPH, 100LPH, 120 LPH and mass flow rate of cold water as 20 LPH, 30 LPH, 40 LPH, 50 LPH, and 60 LPH. Then 40 C, 45 ºC, 50 ºC, 55 C, 60 ºC are the temperatures of hot water at inlet are maintained. To find some various physical parameters of Qc , hc , Re ,, Pr , Rth. The maximum effectiveness of the investigation obtained from condition of Thi 60 C, Tci 32 C and 100 LPH mhi, 60 LPH mci the maximum effectiveness attained as 57.25. Then the mhi as 100 LPH, mci as 60 LPH and Thi at 40 C as 37.6%. It shows the effectiveness get increased about 34.3 to the maximum conditions.

Comparison of Heat Transfer in Solar Collectors With Heat-Pipe Versus Flow-Through Absorbers

1987 ◽  
Vol 109 (4) ◽  
pp. 253-258 ◽  
Author(s):  
J. R. Hull
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Collector ◽  
Hot Water ◽  
Solar Collectors ◽  
Heat Transfer Characteristics ◽  
Absorption Chiller ◽  
Transfer Characteristics ◽  
Proper Design ◽  
Flow Through

Analysis of heat transfer in solar collectors with heat-pipe absorbers is compared to that for collectors with flow-through absorbers for systems that produce hot water or other heated fluids. In these applications the heat-pipe absorber suffers a heat transfer penalty compared with the flow-through absorber, but in many cases the penalty can be minimized by proper design at the heat-pipe condenser and system manifold. When the solar collector is used to drive an absorption chiller, the heat-pipe absorber has better heat transfer characteristics than the flow-through absorber.

Thermal Performance Analysis of a Novel U-Tube Evacuated Tube Solar Collector

2020 ◽  
Author(s):  
Celine S. L. Lim ◽  
Vivek R. Pawar ◽  
Sarvenaz Sobhansarbandi
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Thermal Performance ◽  
Solar Collector ◽  
Performance Comparison ◽  
Heat Transfer Fluid ◽  
Cfd Modeling ◽  
Ansys Fluent ◽  
Evacuated Tube Solar Collector ◽  
Evacuated Tube

Abstract Solar water heating (SWH) systems are the most common application of renewable energy technology that converts solar radiation into useful energy for domestic/industrial activities. The novelty of this study is the design of a new SWH that combines the heat transfer and storage both in a single unit. The selected type of collector for this purpose is an evacuated tube solar collector (ETC). The new design of the ETC has been developed by applying a U-tube inside the collector which contains the heat transfer fluid (HTF). The HTF flows into an external heat exchanger that transfers heat to the water. The implementation of sugar alcohol namely Erythritol (C4H10O4) as the HTF for moderate operating temperature applications was investigated. Moreover, the utilization of solid-liquid phase change material, Tritriacontane paraffin (C33H68), inside the ETC, allows direct heat storage on the system and delayed release of heat. A computational fluid dynamics (CFD) modeling of a single U-tube ETC is performed using ANSYS Fluent in stagnation (on-demand) operation. A 3D model of the ETC is developed and the appropriate boundary conditions are applied. Moreover, the thermal performance comparison of U-tube vs heat pipe ETC has been done. The results from this study shows the maximum fin temperature difference of 46°C of U-tube ETC compared with heat pipe ETC.

Study on Collector Efficiency of Flat-Plate-Type Evacuated Solar Collector to Get Hot Water Near 100°C

2010 ◽  
Author(s):  
Shigeki Hirasawa ◽  
Tsuyoshi Kawanami
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Solar Collector ◽  
Storage Tank ◽  
Heat Storage ◽  
Hot Water ◽  
Measured Temperature ◽  
Control Methods ◽  
Collector System ◽  
Collector Efficiency

We studied effects of parameters on collector efficiency of evacuated solar collector system to get hot water near 100°C. Change of temperature in the solar collector system is calculated for a daily change of solar radiation with 5 minutes cloud. Six operation-control methods are examined. Calculation results show that the effect of the control methods on average collector efficiency for one day is small as 1%. Best control method to minimize effect of the cloud on exit temperature fluctuation of the water is that the flow rate of the water is controlled proportional to the solar radiation. Two types of heat storage system are examined: a non-circulating type (supply new water and accumulate heated water in the heat storage tank) and a circulating type (circulating water from the heat storage tank). The non-circulating type is effective to use the solar energy in the daytime, and the circulating type is effective to use solar energy in the evening. Also, we measured temperature of a collector plate under actual solar radiation in a fine day.

scholarly journals Numerical and Experimental Study of an Asymmetric CPC-PVT Solar Collector

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1669 ◽  
Author(s):  
Pouriya Nasseriyan ◽  
Hossein Afzali Gorouh ◽  
João Gomes ◽  
Diogo Cabral ◽  
Mazyar Salmanzadeh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Cells ◽  
Flow Rate ◽  
Tilt Angle ◽  
Solar Collector ◽  
Hot Water ◽  
Back Side ◽  
Cell Temperature ◽  
Compound Parabolic Concentrator ◽  
Operating Cell

Photovoltaic (PV) panels and thermal collectors are commonly known as mature technologies to capture solar energy. The efficiency of PV cells decreases as operating cell temperature increases. Photovoltaic Thermal Collectors (PVT) offer a way to mitigate this performance reduction by coupling solar cells with a thermal absorber that can actively remove the excess heat from the solar cells to the Heat Transfer Fluid (HTF). In order for PVT collectors to effectively counter the negative effects of increased operating cell temperature, it is fundamental to have an adequate heat transfer from the cells to the HTF. This paper analyzes the operating temperature of the cells in a low concentrating PVT solar collector, by means of both experimental and Computational Fluid Dynamics (CFD) simulation results on the Solarus asymmetric Compound Parabolic Concentrator (CPC) PowerCollector (PC). The PC solar collector features a Compound Parabolic Concentrator (CPC) reflector geometry called the Maximum Reflector Concentration (MaReCo) geometry. This collector is suited for applications such as Domestic Hot Water (DHW). An experimental setup was installed in the outdoor testing laboratory at Gävle University (Sweden) with the ability to measure ambient, cell and HTF temperature, flow rate and solar radiation. The experimental results were validated by means of an in-house developed CFD model. Based on the validated model, the effect of collector tilt angle, HTF, insulation (on the back side of the reflector), receiver material and front glass on the collector performance were considered. The impact of tilt angle is more pronounced on the thermal production than the electrical one. Furthermore, the HTF recirculation with an average temperature of 35.1 °C and 2.2 L/min flow rate showed that the electrical yield can increase by 25%. On the other hand, by using insulation, the thermal yield increases up to 3% when working at a temperature of 23 °C above ambient.

Extreme Seeking for the Optimal Design of the Thermal Energy Storage Tank in a Trough Solar Collector System

2013 ◽  
Vol 448-453 ◽  
pp. 1525-1528
Author(s):  
Guang Yu Liu ◽  
Fen Xu ◽  
Guo Qiang Shen ◽  
Ren Quan Lu
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Optimal Design ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Solar Collector ◽  
Storage Tank ◽  
Main Idea ◽  
Dynamical Process ◽  
Collector System

An extreme seeking (ES) method is given for the optimal design of the thermal energy storage (TES) tank in a trough solar collector system. The energy storage tank in such a solar energy collector performs a filter which regulates the heat transfer in some applications. It is desirable that the volume of the TES tank is optimized in terms of the best performance of heat regulation. The main idea is to construct a simulation scheme that emulates repeatedly the dynamical process and varies the key parameter of the tank at all iterations. The governing algorithm is a convex optimization. A case study that incorporates the above method is examined in the city of a province in China. It is shown in the numerical results that the volume of the TES tank is key variable that influences the performance of heat transfer; the proposed ES method is effective to seek the optimal volume.

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

scholarly journals ANALISYS OF THERMAL EFFICIENCY OF A MODIFIED SOLAR COLLECTOR TYPE EVACUATED TUBE

2014 ◽  
Vol 13 (1) ◽  
pp. 03
Author(s):  
E. Avallone ◽  
A. I. Sato ◽  
V. L. Scalon ◽  
A. Padilha
Keyword(s):  
Solar Collector ◽  
Renewable Energy Sources ◽  
Experimental Tests ◽  
Clean Energy ◽  
Hot Water ◽  
Energy Sources ◽  
Transient Heat Flow ◽  
Important Approach ◽  
Experimental Problem ◽  
Evacuated Tube

The need of renewable energy sources due to climate change and thus the search for clean energy sources, justify the growing investment on new types of solar collectors. The research has contributed to this expansion in the scope of solar concentrator collectors, with the efficiency as the main goal. Many works have been developed in order to optimize the thermal stratification of the fluid inside the tubes and heat reservoirs, as well as mathematical modeling considering the problem as transient heat flow as boundary condition. In this work is studied experimentally, the heating of the water by solar collector modified from the conventional evacuated tube, focusing on efficiency. With the help of CFD software, a theoretical analysis is done to visualize the phenomenon, assuming the same boundary conditions and geometric experimental problem. An important approach concerns the physical separation of the flows of both cold and hot water inside the evacuated tube. The system performance was analyzed using experimental tests performed outdoors with sunlight.

Sign in / Sign up

Export Citation Format

Share Document