International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
www.irjet.net
DESIGN AND DEMONSTRATION OF HEAT PIPE BASED WASTE HEAT RECOVERY SYSTEM S. Venkateswarlu1, Srinivasa Rao Gampala2, Ambadipudi Sunil3, 1
Assoc. Prof. Dept. of Mechanical, SBIT Khammam, Telangana State, India 2Asst.
Prof. Dept. of Mechanical, SBIT Khammam, Telangana state, India
3Asst.
Prof. Dept. of Mechanical, SBIT Khammam, Telangana state, India
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Abstract - A heat exchanger is a device used to transfer
heat between a solid object and a fluid, or between two or more fluids. They are widely used in space heating, refrigeration, air conditioning, etc. are called as conventional heat exchanger. Where conventional heat exchangers not effectively utilized, heat pipe is used as an alternate type of heat exchanger. A heat pipe is a passive heat transfer device which transfers heat from a source to sink by alternate evaporation and condensation of fluid inside a sealed system with temperature drop of 5°C per meter length of pipe. Heat pipe is a stationary device and also it does not have any moving parts. It has three basic components the container, working fluid and the capillary structure. A heat pipe allows transfer thermal energy (heat) over a distance very efficiently. The transfer occurs quickly and with very little temperature loss across the distance. Over a six inch length, the thermal conductivity of the heat pipe can be 100 times greater than a comparable copper rod. A heat pipe is a hollow aluminum or copper tube, sealed at both ends, and filled with a capillary wicking material that is saturated with a liquid. When heat is applied to one end, the liquid at that end absorbs the heat and evaporates. The vapour travels to the other end where it is cooled and condenses back to liquid form, releasing the heat it had absorbed. Key Words: Heat pipe, condensation, evaporation, capillary wicking, thermal conductivity etc. 1.
INTRODUCTION Heat pipe is also a type of heat exchanger. This pipe is used where the conventional heat exchangers are not used. The origin of this heat pipe is during Second World War. The idea of heat pipe was first suggested by R.S. Gaugler in 1942. In 1964 – G.M. Grover published Research paper and coined name Heat Pipe and invented Heat Pipe. The first heat pipe that Grover built used water as working fluid. On April 5, 1967 the first “zero g” demonstration of a heat pipe was conducted by group of engineers of the Los Alamos Scientific Laboratory. In 1968 RCA developed a heat pipe for transistors used in Aircraft transmitters; this is the first commercial application of Heat pipe. Heat pipes offer high effective thermal conductivities (5,000 W/mK to 200,000 © 2017, IRJET
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Impact Factor value: 5.181
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W/mK), energy-efficiency, light weight, low cost and the flexibility of many different size and shape options. As passive heat transfer systems, 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. Heat pipes transfer heat more efficiently and evenly than solid conductors such as aluminium or copper because of their lower total thermal resistance.[1] The heat pipe is filled with a small quantity of working fluid (water, acetone, nitrogen, methanol, ammonia or sodium). Heat is absorbed by vaporizing the working fluid. The vapour transports heat to the condenser region where the condensed vapour releases heat to a cooling medium. The condensed working fluid is returned to the evaporator by gravity, or by the heat pipe's wick structure, creating capillary action [2]. Both cylindrical and planer heat pipe variants have an inner surface lined with a capillary wicking material. This experiment shows effectiveness of heat pipe for heat conduction compared to a metallic rod (Copper in our experiment) by comparing its heat removal rate. 1.1 Structure of Heat Pipe: It consists of a hollow tube in which annular space is lined with wick structure. The hollow tube is first vacuumed, then charged with working fluid and hermitically sealed. A heat pipe in principle divided into 3 parts they are Evaporator, Adiabatic section, Condenser. The driving force that transports the condensed working liquid through the wick to the evaporator is provided by capillary pressure. Working fluids that are employed in heat pipes have concave facing menisci (wetting liquids) as opposed to convex facing menisci (non-wetting liquids). Contact angle is defined as the angle between the solid and vapour regions. Wetting fluids have angles between 0 and 90 degrees. Non wetting fluids have angles between 90 and 180 degrees. 1.1 Method: The heat pipe and copper rod should be in the test section in a vertical position, similar to what is shown in the figure. Three K- type thermocouples are placed at different locations on the periphery for both heat pipe and copper rod. These ISO 9001:2008 Certified Journal
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