Fabrication and Performance Optimization of Parabolic Trough

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 09, 2015 | ISSN (online): 2321-0613

Fabrication and Performance Optimization of Parabolic Trough Ankur Garg1 Kuldeep Singh2 1,2 Assistant Professor 1,2 Department of Mechanical Engineering 1,2 Geeta Institute of Management and Technology, Kanipla, Kurukshetra Abstract— This paper was concerned with an experimental study of parabolic trough collector designed and manufactured. A parabolic trough solar collector uses three reflecting material stainless steel, aluminum foil and mirror glass strips affix on cloth in the shape of a parabolic cylinder to reflect and concentrate sun radiations towards an absorber tube located at the focus line of the parabolic cylinder. The receiver absorbs the incoming radiations and transforms them into thermal energy, the latter being transported and collected by a fluid medium circulating within the absorber tube. To improve performance and reduce costs direct steam generation in the collector has been proposed. The Designing and Fabrication of parabolic trough solar water heater for water heating was executed, the procedure employed includes design, construction and testing stages.

The model which is made up of reflector surface, reflector support, absorber pipe and a stand with manual tracking arrangement was fabricated using locally sourced material for rural applications point of view. In this paper the efficiency of parabolic trough collectors is compared on the basis of different reflecting surfaces (current SEGS plants).

The model is based on absorber fluid temperature so it can be used to predict the performance of the collector with any working fluid. We determined the performance of PTSC on the basis of different reflecting surfaces.

Key words: Solar Energy, Parabolic Trough Concentrator, Fabrication, Thermal Performance I. INTRODUCTION The main objective of this article is to produce hot water with different reflecting surface. In the 1980s, most of the studies on performance improvement tried to enhance the individual components in the collector. Efforts were made to optimize the operating conditions and performance variables for various conditions (Mather 1980, Behrendorff and Tanner 1982). A brief analysis is also carried out to choose the best reflective material in terms of efficiency and cost.

The main objective of present study is to design, fabrication, experimental analysis and cost analysis of Prototype PTC with different concentrating materials for hot water generation and to check its feasibility for further application.

Fig. 1: Prototype of Parabolic Trough

A. Parabolic Trough Concentrator A parabolic trough concentrator (PTSC) is made of an aluminium sheet which is covered by a cloth on which rectangular mirror strips (1.2m*0.05m) are pasted An absorber tube (copper) was taken and the efficiencies of the PTSC were compared with three different reflectors. The PTSC was made of appropriate materials and was manually tracked. They were designed with principal focus at 0.3m The dimensions of the collector were width, 1.2m, Collector length 1.20m, aperture area 1.40 The absorber tube carried water as the heat transfer fluid. The concentration ratio of the solar concentrator was 11.04. The concentrator testing was carried out for each case of absorber tube with glass cover tube of different diameter. The manual tracking is done according to the movement of sun from morning to evening.

B. Water Tank There is a rectangular water tank that I used in this prototype of PTSC. The capacity of water tank was 15 liter and the material was tin. A pump of 25 Watt was inserted inside the water tank for the circulation of fluid. A thermocouple was also inserted inside the water tank in order to measure the temperature. There was a hole on the top of the tank in order to put the thermocouple and pump. Pump is run by the electric supply. Water tank was insulated by soflon.

C. Measuring Devices and Instruments Different parameters are measured in this work; these include:  

Inlet and Outlet Air Temperature Solar radiation intensity RTD PT100 thermocouples are used to measure the temperatures at different points. The thermocouples are connected with a digital temperature indicator that shows the temperature with a resolution of 0.1 . The solar radiation intensity is measured during the day using a Pyranometer (model CM11), supplied by Kipp and Zonen, Holland.

The experimental data are recorded at regular intervals of 1hr during the daytime. The experiments were carried out during some selected clear sky days in the month of April-May2012.

D. System Operation The following procedure was used to perform the experiments: 1) The collector was exposed to the sun at least 30 min before the experiment.

2) In each experiment, for 30 min duration, the water mass flow rate passing through the absorber was maintained constant.

3) The collector was tracked with the sun manually by inspecting the reflecting rays falling on the absorber.

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Fabrication and Performance Optimization of Parabolic Trough (IJSRD/Vol. 3/Issue 09/2015/116)

4) After the preparation of the apparatus, the above readings were recorded:  Mean water inlet temperature.  Mean water outlet temperature.  Total and diffused radiation falling on the collector surface.  Mass of collected water E. Analysis of Experimental Data The thermal performance of the parabolic solar concentrator can be estimated by the solar collector efficiency factor (η), which is defined as the ratio of the net heat gain and the solar radiation energy based on diffuse reflection area of solar collector AP [Ma (2015)]. η= (Tout – Tin)/I0AP F. Experimental results and discussion I have considered three cases in order to compare the performance of PTSC. 1) Case 1: Bare Copper Tube with Stainless Steel Reflector:

Fig. 2: Graph:1 Variation of collector water temperature and solar radiation intensity through the day in bare copper tube with stainless steel as reflecting surface.

This graph shows that the variation of temperature with solar intensity .In this case temperature at 8am was 25 oC. As the day progress the maximum temperature we got was 60.4oC at 2pm.

This was the peak temperature that I got in this case. This gives the better performance as compared to the flat plate collector.

Fig. 4: Graph: 3 Variation of Thermal efficiency with solar intensity through the day in bare copper tube with stainless steel as reflecting surface.

The figure show’s that the thermal efficiencies was going to decrease as the day progress.

2) Case 2: Bare copper tube with aluminum foil as reflecting surface:

Fig. 5: Graph: 4 Variation of collector water temperature and solar radiation intensity through the day in bare copper tube with aluminum foil as reflecting surface.

This graph shows that the variation of temperature with solar intensity .In this case temperature at 8am was 25 o C . As the day progress the maximum temperature we got was 68.1 oC at 1pm.

Fig. 6: Graph: 5 Variation of useful heat gain with solar intensity through the day in bare copper tube with aluminum foil as reflecting surface.

The results & Reflectivity of aluminum foil reflector is better than that of the stainless steel.

Fig. 3: Graph: 2 Variation of useful heat gain with solar intensity through the day in bare copper tube with stainless steel as reflecting surface.

It will be noted that the general pattern of variation of efficiency over a day is the same as that of the useful heat gain because the value of efficiency depends on both the incident beam radiation and the useful heat gain .The useful heat gain was 140 watt during 8am-9am. As the day progress the useful heat gain and thermal efficiencies was going to decrease because the temperature of fluid was going to increase.

Fig. 7: Graph: 6 Variation of Thermal efficiency with solar intensity through the day in bare copper tube with aluminum foil as reflecting surface.

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Fabrication and Performance Optimization of Parabolic Trough (IJSRD/Vol. 3/Issue 09/2015/116)

The figure show’s that the thermal efficiencies in this case is 31.93%.As the day progress the thermal efficiencies was going to decrease because the water become hot .so due to this the heat gaining capacity of the fluid decreased.

3) Case 3: Bare copper tube with mirror strips as reflecting surface:

Fig. 8: Graph: 7 Variation of collector water temperature and solar radiation intensity through the day in bare copper tube with mirror strips as reflecting surface This graph shows that the variation of temperature with solar intensity .In this case temperature at 8am was 25oC. As the day progress the maximum temperature we got was 75.0 oC at 1pm.This case gives the best result in the case of bare copper tube in among all three reflecting surfaces. It gives the better performance as compared to the flat plate collector.

are 18.34%. The efficiencies observed for parabolic trough concentrator demonstrates that this technology with appropriate absorber tube systems can produce hot water that is hot enough for solar thermal conversion power systems. In this case higher temperatures and higher efficiencies would be realized. On the other hand use of stainless steel sheet and aluminum foil led to low reflectivity resulting to low operating efficiency of the concentrating collector. Use of copper tube receiver with mirror strips as reflecting material surface and enclosing it inside a transparent medium and evacuating it and also surface treatment of receiver as evident with Euro trough, Sky fuel trough, Luz collectors’ etc would significantly improve the efficiencies of PTSC and useful heat gain is calculated by Q = (From the above experimentation we conclude that the maximum temperature obtained from PTSC is 75.00C while the lowest temperature is 60.40C and the average temperature obtained is 650C.The temperature variation of PTSC depend upon the reflecting surface (reflectivity) and the amount of solar intensity falls on the PTSC. Useful heat gain mainly depend upon the temperature difference between inlet and outlet in 1 hour .The maximum useful heat gain is 280 watt in the case of glass mirror surface with glass tube. The maximum temperature rise also comes out in the case of glass mirror as reflector with glass tube used over the copper tube .So we can further improve the efficiency of PTSC by improving its tracking mode. The Prototype PTC can further be utilized in various practical applications like air heating, process heating and further steam can also be generated with more aperture area.

ACKNOWLEDGMENT The parabolic solar concentrator in this project was provided

by M.D. H.S. Chadha, Sunson Energy Devices (P) LTD, New Delhi, India.

REFERENCES

Fig. 9: Graph: 8 Variation of useful heat gain with solar intensity through the day in bare copper tube with mirror strips as reflecting surface.

Fig. 10: Graph: 9 Variation of Thermal efficiency with solar intensity through the day in bare copper tube with mirror strips as reflecting surface.

II. CONCLUSIONS In this article, a study was made to enhance Kenyan research in solar thermal for hot water generation by use of appropriate materials. The overall thermal efficiencies for the PTSC were as follows: when without glass cover in copper tube receiver: with three reflecting material, stainless steel 12.55% ,aluminum foil 15.52% , and in mirror strips

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Fabrication and Performance Optimization of Parabolic Trough (IJSRD/Vol. 3/Issue 09/2015/116)

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