HEAT EXCHANGER STUDY AND OPTIMIZATION APPROACH FOR ENGINE EFFICIENCY IMPROVEMENT

Abstract

The scenario for the off-road machines during the next years will feature vehicles with relevant changes in terms, for example, of engine operative velocity and passive braking force reduction, with a concurrent increase (some 40 %) of thermal energy exchange needs by the heat exchanger. Engine, and hydraulic oil, temperatures will vary in function of actual requested power, to reduce the NOx production. This aspect, linked to the need to have an optimized engine layout (reduction of radiator dimensions) is the base of the work presented in the paper. The heat exchanger optimization is needed to obtain smaller, lighter, but at the same time more efficient, heat exchangers; this paper shows how it is possible to apply a CFD-mathematical approach on a cross-flow radiator with the aim to obtain a more efficient heat exchanger surface and reduced global dimensions. The approach used, and described in this work, made the performance evaluation possible not only on a single radiator, but on a complete production family variable both in dimension and technical characteristics. The approach is to split the exchanger into sub-domains having homogeneous boundary conditions, both in the cold and hot side, in order to collect on the WHTC (Wall Heat Transfer Coefficient) and the pressure drop. Individual results will be used as building blocks in order to have a reliable yet flexible estimate of the exchanger performance under different environmental conditions and dimensions. The results are encouraging and show the possibility to develop a new, optimized, radiator family, using a flexible and efficient design strategy. Keywords: heat exchanger, earth moving machineries, engine efficiency, optimization approach.