Diesel engine has been improved by installation of turbocharger which increase the quantity of charge air. If intercooler, which function is the cooling of intake air compressed and heated through turbocharger, is added in this engine, turbocharged engine is further reinforced in its power and performances.
In this study, in order to develop a performance rating method of air-to-air intercooler as well as its design data, the performance rating method of compact heat exchanger is applied to that of air-to-air intercooler, where the convection heat transfer coefficient and the flow friction coefficient are calculated by following two methods : one is the method using the existing experimental data for plate fin surface geometry, the other is the method using experimental equations for circular tube with a equivalent hydraulic diameter of non-circular duct. The testing apparatus is designed to test the performance of $L\ddot{a}ngerer$ ＆ Reich Intercooler, where hot air is supplied by a roots blower instead of automobile turbocharger and cold air is supplied by a $590^{\phi}$ automobile radiator fan.
From the comparisons between calculations and experimental data for the performance rating of the intercooler, the following results are obtained.
1. The calculation of outlet temperature and intercooler effectiveness agree with the experiments very well.
2. However, the calculation of pressure drop through intercooler differ from the experiment by 20% approximately. It is seemed that this is due to too simple configuration modeling of inlet and outlet ducts of the intercooler.
3. It is also supposed that this apparatus is good enough in performance test of other air-to-air intercooler because the heat balances between hot air side and cold air side is satisfied each other within 3%.
