Numerical Simulation of Effect of Relative Humidity on Pressure Drop Across Crossflow Heat Exchanger with Staggered Tube Arrays at Its Extreme Operational Temperature

Cross flow heat exchangers form a common and an essential component of many industrial applications and solutions. Heat exchange in these heat exchangers depends upon the Reynolds number and thermophysical properties of air and effective surface area. For the flowing cooling air, the pressure drop across the heat exchanger dictates the amount of resistance the fluid faces while flowing through it or the power needed to move the flow across the tubes. In this research, the pressure drop athwart an elliptical tubed cross flow heat exchanger available in the facility has been studied numerically at its maximum operating temperature of 323K with Reynolds number ranging from 5000 to 20000. The simulations are performed with increasing relative humidity from 0% to 80% in the cooling air. The thermophysical properties of humid air are incorporated. The relative humidity is simulated in the form of mass fractions of water vapours in the air. The effect of this change in humidity content is examined on the pressure difference between the inlet and outlet of the heat exchanger. The results depict the decline in pressure drop up to 5.5% with the increasing humidity content from 0% to 80%. The decreasing phenomenon is studied on the selected Reynolds numbers of the mentioned range. The research shows that the change in pressure drop due to increasing relative humidity in the cooling air does not depend on the Reynolds number but it depends on the moisture content present in the air. This paper provides an instrument to examine the pressure drop characteristics across cross flow heat exchangers with elliptical arrays of tubes in humid air conditions.