Evaluation of performance characteristics of Plate Fin Heat Exchanger

Heat exchangers are main equipmants in the process industries . Heat exchangers having high heat transfer surface area per unit volume(725m 2 /m 3 ) are called compact heat exchangers. Plate fin heat exchanger is one of the type of compact heat exchanger which is widely used in automobiles, cryogenics, liquifires and chemical industries need to be highly efficient becausein gas liquification,effectiveness is the main parameter which denotes the performance of the heat exchangers in terms of heat transfer rate between the lowing fluids.The effectiveness of thesecompact heat exchangers before putting them in to operation should be checked and it should not be below 90 percent in case of gas lequification. The trial is conducted under steady condition i.e the mass flow rate for both sides of fluid stream is same ,and the experiment is carried out at different mass flow rates. Various correlations are available in the literature for estimation of heat transfer and flow friction characteristics of the plate fin heat exchanger, so the various performance characteristics like effectiveness, heat transfer coefficient and pressure drop obtained through experiments are compared with the values obtained from different correlations . A heat exchanger is a device to transfer heat from a hot flu- id to cold fluid across an impermeable wall. Fundamental of heat exchanger principle is to facilitate an efficient heat flow from hot fluid to cold fluid. This heat flow is a direct function of the temperature difference between the two fluids, the area where heat is transferred, and the conductive/convective properties of the fluid and the flow state. In order to increase the heat transfer in, assuming that the heat transfer coeffi- cient cannot be changed, the area or the temperature dif- ferences have to be increased. Usually, the best solution is that the heat transfer surface area is extended although in- creasing the temperature difference is logical, too. In reality, it may not be much meaningful to increase the temperature dif- ference because either a hotter fluid should be supplied to the heat exchanger or the heat should be transferred to a colder fluid where neither of them are usually available. For both cases either to supply the hot fluid at high temperature or cold fluid at lower temperature extra work has to be done. Fur- thermore increasing the temperature difference more than enough will cause unwanted thermal stresses on the met- al surfaces between two fluids. This usually results in the deformation and also decreases the lifespan of those materials. As a result of these facts, increasing the heat transfer surface area generally is the best engineering approach. A large amount of study has been conducted to analyze the heat transfer and pressure drop characteristics of compact heat exchangers in the past few decades. But this study mainly fo- cuses on the Offset strip fins type of plate fin heat exchanger. And therefore the emphasis has been given on the literatures related to the prediction of j and f factors and the thermal per- formance testing of heat exchangers.