A mathematical model which predicts the cooling system performance for a rally car is derived in this study. A case study vehicle was made available by a local manufacturer for evaluation of the cooling system. Two heat exchangers compatible for the vehicle were tested in a controlled wind tunnel environment to determine its heat transfer characteristics. Including the relationship between fluid flows and vehicle speed, a function resulted through which the cooling system performance can be predicted. Including the heat generated by the engine to be dissipated by the cooling system and the effect of ambient conditions on heat generated and dissipated, an energy balance results. Using the energy balance a contour plot is generated which predicts the suitability of the heat exchanger at various ambient conditions. The tool thus allows the user to assess the cooling system on the day of the race, highlighting whether the required cooling will be achieved. / Dissertation (MEng(Mechanical))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

The simulation of vehicle engine cooling validation in a Climatic chamber will benefit all vehicle manufacturers that are responsible for the design or the localization of parts used in a vehicle's engine cooling system. The ability to test the vehicle in-house allows testing at any time of the year; it provides repeatable and comparative data, and accelerates component level approval, which in itself reduces program timing and cost. For this dissertation road level testing was conducted in Upington using a TD1200 Superflow towing dynamometer, while the in-house testing was performed on a ROTOTEST chassis dynamometer in a Climatic chamber. All tests were conducted according to GENERAL MOTORS SOUTH AFRICA global testing standards. Statistical analyses of the test data were used to determine the relationship between parameters measured and results obtained. The major contributors to the simulation process was identified and implemented to improve measurement quality and test results. The result was an accurate simulation between road and chamber testing, hence the possibility of moving away from road testing and conduct simulated chamber testing. The presented dissertation is useful for the understanding of basic vehicle cooling testing and the methodology of simulated testing in an environmentally controlled chamber.

The modelling and control method of a vehicle climatronic system, based on MATLAB/SIMULINK, is presented. In order to achieve high modelling accuracy, a developed simulation model library is introduced. The modelling approach is described and the developed models are validated with some of experimental data obtained. The models are nonlinear, independent of fluid type and based on thermo-dynamic principles. Analysis of the cooling circuit modelling and empirical real-time control models are created by using Fuzzy logic controller and Stateflow. Both of control input and output are implemented essentially at original vehicle CAN-Bus system. Feasible digital automatic control strategy basic to fuzzy theory, hardware and software solution are given. The simulation experiment is achieved with the Hardware-in-Loop technology. This control methodology is easily operated and worth applying for any further studies or methods.