My research activities are in the areas of (i) compact heat exchangers: perforated plate type (PPHEs), (ii) wave expansion based refrigerators, (iii) thermoacoustic devices and (iv) heat transfer using nano-fluids. The PPHEs are constructed of several high thermal conductivity perforated plates. The plates are alternately arranged with insulating spacers in between. Several PPHEs were built by diffusion bonding between perforated copper plates and stainless steel spacers. Perforated copper plates were fabricated by photo chemical etching. The perforations are of 0.6 mm diameter while the plate and spacer thickness are 0.4 and 0.5 mm respectively. The fabricated heat exchangers, having 75 and 100 plates, were tested for their performance at cryogenic temperature.
A wave expander is a device where energy is transferred from one fluid to the other through a shock wave. It is usually constructed of a long tube in which a high pressure gas is suddenly released through the rotation of a valve. In one part of the rotation the tube is exposed to high pressure when a shock wave is created at the interface of the inlet gas and the existing gas inside the tube. The tube is connected to the low pressure in the next part of the rotation of the valve. In this period the rarefied gas near the inlet to the tube is further expanded causing a drop in temperature. Preliminary studies showed very encouraging results. Presently a complete refrigeration system on this principle is under construction.
Thermoacoustic devices exploit a temperature gradient to produce powerful pressure waves. Thermoacoustic processes are associated with the compression and rarefaction of the working gas as an acoustic wave propagates through closely spaced plates in the stack of a thermoacoustic device. Presently four Ph.D and four M. Tech students are working on the above mentioned area.
Design and development of perforated plate heat exchangers for cooling of gaseous Helium by using liquid Hydrogen ISRO, IIT KHARAGPUR CELL
Lam Ratna Raju
Area of Research: Heat Transfer and Heat Exchanger
Sudeep Kumar Gupta
Area of Research: Thermoacoustic
Soumya Kanti Hazra
Area of Research: Heat transfer using nano fluid
Area of Research: Cryorefrigeration