Design of Radiators for Low Flow Cooling Systems

There has been a recent surge of interest in low flow engine cooling systems. In such systems, a relatively low flow of coolant, compared to conventional engine cooling systems, is subject to a relatively large temperature drop through the radiator. The resulting low temperature coolant is used to cool the engine's turbocharger intercooler in order to provide lower intake manifold temperatures, which result in higher power, better fuel economy, improved emissions and extended engine life. The performance requirements for low flow radiators have required innovative new designs from the radiator industry. While there are many similarities between low flow and conventional high flow radiators, the differences are significant, and include the need for multipass coolant circuitry, sealed tank baffles, deaeration bleed valves, auxiliary fill ports, tube turbulation and high strength tube to header joints. Design considerations regarding these features are discussed and performance of a typical low flow radiator is described.