Numerical Simulation and Analysis of Chevron Type Heat Exchangers for Thermal Camouflage of Buried Structures

The reports have shown that the existed thermal I.R sensors are able to sense the temperature difference 2°C to 8 °C between buried spaces exhaust air and ambient with a good accuracy. In this paper, in order to minimize the probability of identifying safe buried structures by spy satellites and increasing their thermal camouflage, a plate heat exchanger for reducing the temperature of the exhaust air of buildings to ambient temperature is proposed. The technical specification of the proposed chevron type heat exchanger is determined based on the traditional design approaches. A MATLAB program code is developed for analysis of these heat exchangers and finding the optimized angle of grooves and estimating number of plates. The ANSYS software is also used to analysis the effects of plate materials on total heat transfer and their strength to deformation. Then the designed heat exchanger, under the same operating conditions with the analytical approach, is analyzed again by the ASPEN software. The analytical solutions and the numerical results were validated with approved results reported in the literature and a good consistency was observed. Finally as a case study, the groove angles, required number of plates and other geometrically data is calculated for a heat exchanger of a safe buried structure. The results showed that a plate heat exchanger, made by 161 stainless steel plates with 2m in height and 45 degrees groove angle, is needed for thermal camouflage of a safe buried building with 10000 CFM exhaust air at 22°C to an ambient at -20°C.