Research Projects

Pulsating Heat Pipe (PHP) is an efficient passive heat transfer device with high effective thermal conductivity. This device is of low cost and highly flexible structure, which makes it suitable for applications such as electronic cooling, waste heat recovery, solar heat transfer etc. Present study is to develop a novel coil type Pulsating Heat Pipe as heat transfer enhancement devise for heat exchangers. This application of PHP has never been reported before and very much required as there is a limit to the heat transfer enhancement with current passive method used in heat exchangers. Heat exchangers are prominent heat transfer device used in almost all the industries. Double tube heat exchangers are still the most preferred type due to simplicity in geometry and operation. Many passive heat transfer enhancement techniques are being used in the double tube heat exchanger, such as insertion of twisted tape, vortex generators, changing the geometry of the inner tube etc. However, there is a limitation to the level to which heat transfer can be enhanced using passive techniques. For further increase in the heat transfer, active methods need to be used, which will increase the total energy consumption. Therefor it is a necessity to introduce new passive techniques or devises for further considerable increase in the heat transfer. Pulsating heat pipe can be used for considerable enhancement of heat transfer coefficient in the annular region of double pipe heat exchanger by increasing the turbulence as well as acting as fins of very high thermal conductivity. PHP, which is fabricated to a geometry similar to wire coil, can be wound around the outer periphery of the inner tube. This increases the heat transfer coefficient of the annular fluid flow by increasing the turbulence. A portion of each turn of PHP is attached to inner pipe, and this part acts as the evaporator region. The condenser portion of each turn of PHP need to be detached from the inner tube and extended into the annular region and acts as super conducting fins, as the effective thermal conductivity of PHP can be more than 10,000W/mK. This combined effect of increased turbulence and high thermal conductive fin reduces considerably the thermal resistance between the heat transferring fluids. Detailed investigation on the thermal performance of this coil type PHP forms the first part of the present investigation. Experimental and numerical studies will be conducted for closed end and closed loop PHP. Suitable PHP working fluid for different temperature ranges will also be identified. The application of this coil type PHP to an air-water double pipe heat exchanger is the next part of the study. Heat transfer enhancement of cold air flowing in the outer tube can be increased with the application of PHP around the periphery of the inner tube with hot water. Numerical studies will be conducted to find the optimum geometry of the PHP for the maximum heat transfer with minimum pressure drop.

Pulsating Heat Pipe, Double pipe heat exchanger, heat transfer enhancement, super conducting fins, thermal performance