Thermo Hydraulic Performance of Plate Fin Heat Exchanger

Abstract

The present study aims to propose a selection and design methodology of com-pact plate fin heat exchanger to Ingersoll Rand ( India ) Limited. Ingersoll Rand manufactures reciprocating, centrifugal and screw compressors. For their screw compressors plate fin heat exchanger is used in compressor circuit. Main purpose of this heat exchanger is to cool compressed air as well as oil used for cooling and lubrication purpose. As air and oil coolers are combined into one unit, a proper design procedure of such a plate fin heat exchanger is required. In this respect present study is carried out to full fill requirement of Ingersoll Rand ( India ) Limited. In present study the design of plate fin heat exchanger is carried out base on the input parameters available from Ingersoll Rand. The various input parameters considered in the present design methodology are : inlet temperature, inlet pressure, mass flow rate of fluid and allowable pressure drop. As per the design methodology of plate fin heat exchanger, a crucial parameters such as colburn factor and friction factor are required. Values of these parameters can be obtained from Kays and London (1984). Further, there are some experi-mental correlation also available in the literature. However it should be noted that these correlations are applicable to particular condition and hence have limited applicability. A more generalised correlations for friction factor and colburn factor are proposed through the numerical simulations of fluid flow and heat transfer in offset strip fin. Here, the simulations are carried out for various values of fin height, fin pitch and fin length. The present study also aims in selection of fin configuration for required heat duty. In this regards a novel methodology is developed to select an appropriate fin by comparing different types and size of fin. This comparison is based on different constraints. These constraints are fixed frontal area, fixed heat exchanger volume and fixed pumping power. According to the constrains different graphs are generated for plain fin, offset strip fin and louvered fin. From these graphs one can choose best fin for particular application. Furthermore the selection method is extended for proper thermal design procedure of plate fin heat exchanger. Based on this analytical method computer program is developed for sizing of plate fin heat exchanger. The design of plate fin heat exchanger using developed correlation is compared with Kays and London data as well as Manglik and Bergles correlation. Length of heat exchanger in the direction of hot fluid flow obtain from present correlation is 20% less as compare to that of Kays and London data as well as Maglik and bergles correlation. While other dimensions are found to be in good agreement.