Experimental Investigation of Thermal Performance of Ethanol Fluid Wickless Copper Heat Pipe

Experimental Investigation of Thermal Performance of Ethanol Fluid Wickless Copper Heat Pipe

Md.Shahraz Akhtar

M.Tech Scholar

Agnos College of Technology ( R.K.D.F University) Bhopal, MP, India -462033

Sohail Bux

Mechanical Engineering Department

Agnos College of Technology ( R.K.D.F, University), Bhopal, MP, India -462033

Abstract: In this study, the aim is to investigate the thermal performance of ethanol fluid wickless heat pipe . For this purpose, a long evaporative section wickless heat pipe) is designed, constructed and tested at temperatures of 50,60&70C In this work the wickless heat pipe is made of copper tube of 1000mm length of internal diameter 24.4 mm and 1mm thickness. The working fluid employed is ethanol with filling ratio (FR) 40%. The lengths of evaporator, adiabatic & condenser sections are 600, 200 and 200 mm respectively. The wickless heat pipe placed centrally in 2 inch uPVC pipe. The 2 inch uPVC pipe water jackets are provided in both evaporative & condenser section of prescribed length for hot water circulation. Heat source at 50, 60 &70C temperature of hot water taken during experimentation. Immersion water heater was used for water heating process. The Inclination of the wickless heat pipe varies between 0 to 90. Seven different tests were carried out in different orientation angle. The results show that efficiency of wickless heat pipe mode is in range of 47.61% to 73.33%.Experimentally found that the the vertical position as well as 45angle are the best for long evaporative section ethanol fluid wickless heat pipe.

Keywords: Ethanol fluid, wickless heat pipe, Heat pipe, long evaporative section.LES.

1. INTRODUCTION

   Wickless heat pipes are heat transfer devices whose operating principles are based on the evaporation/condensation of a working fluid using the capillary pumping forces (in case of heat pipe) and gravity forces (in case of two phase thermosiphons) to ensure the working fluid circulation.Two- phase (Wickless heat pipes) heat transfer involves the liquid- vapor phase change (boiling and condensation) of a working fluid. Wickless heat pipes offer high effective thermal conductivities, energy-efficiency, light weight, low cost and the flexibility of many different size and shape options. As passive heat transfer systems, Wickless heat pipes offer simple and reliable operation, with high effective thermal conductivity, no moving parts, ability to transport heat over long distances and quiet vibration-free operation. Wickless heat pipes transfer heat more efficiently and evenly than solid conductors such as aluminum or copper because of their lower total thermal resistance. It transfers heat many times faster than pure copper. The wickless heat pipe is filled with a small quantity of working fluid (Ethanol). Heat is absorbed by vaporizing the working fluid. The vapor transports heat to the condenser region where the condensed vapor releases heat

   to a cooling medium like water. The condensed working fluid is returned to the evaporator by gravity, or by the heat pipe's wick structure, creating capillary action. The use of wickless heat pipes offers several advantages regarding flexibility in operation and application, as they are very proficient in transporting heat even under a small temperature difference [1]. Wickless heat pipes are currently utilized in many energy systems according to their needs, in industrial areas and aerospace applications, including the solar system even in comparison with the space heating requirement. Moreover, the environmental issues linked to the use of fossil fuels give great incentives to tie together alternative energies where possible. In the current study we are using Wickless heat pipes We were used wickless heat pipes in three orientations namely horizontal, vertical and inclined. The size of wickless heat pipes was selected according to the size of casing of test rig. The selected wickless heat pipe is of length 1000 mm and diameter 25.4 mm. The main aim of this experiment was to find out the thermal performance of wickless heat pipe.

2. EXPERIMENTAL SETUP

   The experimental setup is designed and constructed at Workshop. The long evaporative section wickless heat pipe is designed and constructed by siddharth solar Technergies, Pune It is made of copper(Cu) tube of 1000 mm length of internal diameter 24.4 mm and1mm thickness. The working fluid employed is ethanol with filling ratio (FR) 40%. The lengths of evaporator, adiabatic & condenser sections are 600, 200 and 200 mm respectively. The maximum heat transfer capacity of wickless heat pipes is 500 W. The pipe was initially evacuated using vacuum pumps (rotary and diffusion pumps) after a series of cleaning processes to remove possible contaminants, which can affect the performance and life of wickless heat pipes. The pipe is first pumped down at the ambient temperature: and then, the pumping is continued while the pipe is heated [3, 4]. Since high vacuums were required, this was a time-consuming process. Following evacuation, the working fluid was sucked into the pipe through a special valving arrangement and the filling tube attached at the upper end was flattened by crimping to a thickness of 0.1to 0.2 mm. This process required up to an hour for pipe. uPVC pipes and their fittings like elbow, reducer, ball valves, caps etc are used in manufacturing of test setup.2 inch and 0.5 inch uPVC pipes and their fittings are used. 2 inch uPVC pipe fitting water

   jackets prepared in work shop and are provided in both evaporative and condensing section of specified length for hot water circulation. Water circulation was done by using

   0.5 hp centrifugal pump. Ball valves are used for controlling the mass flow rate of circulating hot water. The wickless heat pipes placed centrally in 2 inch UPVC pipe. One Cylindrical water tank of diameter 1m was used for storing hot water. Immersion water heater of 2000 Watt capacity was used for water heating process. The role of the adiabatic section is to connect the condenser and evaporator sections together. The length of adiabatic section in this setup is constant which is 200 mm. The wall temperature distribution along the pipe was measured using ten calibrated thermocouples (type K). The thermocouples are inserted in (2) mm grooves, machined in the outer surface of the water circulation jacket pipe wall. An accurate wattmeter is connected to water heater to record the exact power supplied. The temperature was read directly from a digital display. Mass Flow rate of the hot and cold water was determined by measuring the amount of the water over an interval of time. Water inlet and outlet temperatures were measured using two thermocouples. The actual experimental facilities are shown in Fig.01& 02.

   Fig.No-01 Actual heat pipe test setup image.

   Fig No-02 pipe fittings images.

3. FORMULAE USED FOR CALCULATION

   Heat performance solution of wickless heat pipes is based on calorimetrical equation and values from experimental measuring. The same calculations were used at work [5].The following formulae are used for calculation.

   (1)

   t = t2 t1 (2) R= Thot – Tcold//Qin (3)

   Where t is the temperature difference between output and input temperature, m is the mass flow rate of water, c is the specific heat capacity of liquid, R is the overall thermal resistant, Thot & Tcold/ are the average temperature at evaporative section and condensing section, Qin is the total heat input in evaporative section.

4. RESULT AND DISSCUSSION

   The table no-(01) is the performance sheet ofethanol wickless heat pipe. The maximum wickless heat pipe efficiency found 73.33% at 70C heat source temperature in vertical position. During experimentation 67.85% efficiency at 60C also found in 45angle of orientation. Figure (3) illustrates the variation of wickless heat pipe efficiency with mass flow rate at different orientation (0, 15,30,45,60,75,90) angle for different heat source(50C, 60C, 70C).Fig No-04 illustrates Heat performance with different orientation angle for different heat source. Best heat performance 365.75 W was found at vertical position for 0.0385 Kg/Sec mass flow rate of water. Fig No-05 illustrates Variation of overall thermal resistance with heat input for different heat source. Thermal resistance decrease with total heat input. Maximum thermal resistance 0.109278C/W was found at horizontal position for maximum mass flow rate 0.0417 Kg/Sec. Fig No-06 illustrates Variation of overall thermal resistance with tilt angle for different heat source. It was observed that Maximum thermal resistance 0.109278C/W occurs at horizontal position. Figure (7) illustrates the MAT Lab variation of wickless heat pipe efficiency with mass flow rate at different orientation (0, 15,30,45,60,75,90) angle for different heat source(50C, 60C, 70C).

   Table No (01) Performance of ethanol wickless heat pipe.

   Fig No-03 Variation of wickless heat pipe efficiency with mass flow rate at different orientation angle for different heat source.

   Fig No-04 Heat performance with different orientation angle for different heat source.

   Wickless Heat Pipe Working Fluid Ethanol
   Workin g Temp.	Angle	Mass Flow Rate(Kg/Sec)	Wickless Heat Pipe efficiency(% )	Over all Thermal resistance( C/W)
   50C	0	0.0417	47.61905	0.065345
   	15	0.0407	47.82609	0.060579
   	30	0.0400	50	0.053885
   	45	0.0397	65.51724	0.04719
   	60	0.0392	62.06897	0.048436
   	75	0.0388	62.06897	0.048686
   	90	0.0385	66.66667	0.04691
   60C	0	0.0417	47.82609	0.084315
   	15	0.0407	52	0.078802
   	30	0.0400	53.57143	0.070969
   	45	0.0397	67.85714	0.07073
   	60	0.0392	64.28571	0.072007
   	75	0.0388	65.51724	0.069917
   	90	0.0385	70	0.067592
   70C	0	0.0417	52.17391	0.109278
   	15	0.0407	54.16667	0.106914
   	30	0.0400	57.69231	0.098799
   	45	0.0397	65.51724	0.088456
   	60	0.0392	65.51724	0.089877
   	75	0.0388	65.51724	0.090509
   	90	0.0385	73.33333	0.087237

   Fig No-05 Variation of overall thermal resistance with heat input for different heat source.

   Fig No-06 Variation of overall thermal resistance with tilt angle for different heat source.

   Fig No-07 MAT Lab Graph Variation of wickless heat pipe efficiency with mass flow rate at different orientation angle for different heat source.

5. CONCLUSION

Ideal working position of wickless heat pipe is vertical position. wickless heat pipe operate on maximum performance and maximum mass flow transfer in this position. From experimental measuring performance of wickless heat pipe is creating graphic dependences average values of thermal performance from working position of wickless heat pipe. The maximum wickless heat pipe efficiency found 73.33% at 70C heat source temperature in vertical position. During experimentation 67.85% efficiency at 60C also found in 45angle of orientation. This experiment has testified that the ethanol fluid wickless heat pipe is able to operate at any other position as vertical and even at the horizontal position. From results measured performances of wickless heat pipe at various working position discover that the wickless heat pipe is able to operate at inclined position 45and total heat performance transfer is not very different as at vertical position. Due to long evaporative section of wickless heat pipe the heat absorption capacity at evaporative section also found which is maximum 482.3077 W at 70C heat source.

ACKNOWLEDGMENT

The author would like to thank to Head of The Department Prof Sohail Bux for his support and discussions.The authors gratefully acknowledge Dr.V.K.Sethi (Vice chancellor RKDF University Bhopal) , Dr.B.N.Singh (Registrar RKDF University Bhopal ) and Mr.Sunil.Patil (Controller of Examinations RKDF University Bhopal ).The authors gratefully acknowledge the financial support RKDF University Bhopal (MP) India. The authors are also grateful to the anonymous referees who provided detailed and constructive comments.

REFERENCES

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