Development of a set of computational tools to assist the design of automotive refrigeration equipment.

摘要

In this Thesis a model for the main components of an Automotive Air Conditioning cycle (evaporator condenser and compressor) is presented, including a comparison between calculated and measured results for different types of these elements.; The development of the model has been carried out by the Universidad Politécnica de Valencia in co-operation with FASA-RENAULT, under a research project supported by the Spanish Agency for R&D; CICYT.; The input data for the model are the geometry and the inlet conditions and the mass flow rate of the flows. Then the model calculates the outlet conditions and all the performance parameters.; The evaporator and condensor developed model is able to take into account the following aspects of the heat exchangers; any flow configuration, any distribution of fluid speed and temperature at the HE inlets, and refrigerant with water or air as secondary fluid, local evaluation of the thermodynamic properties and the heat transfer and friction coefficients, and longitudinal conduction through the evaporator walls.; The experimental data measured in the test bench of the company for two different evaporator models working with refrigerant R134a have been compared with those predicted by the model for a wide range of operating conditions.; The performed comparison shows that the model is able to predict heat exchangers performance (refrigeration capacity, outlet temperatures and pressures) within a ±5%. This proves the model to be a helpful tool for evaporator design and optimisation.; The compressor developed model is able to analyse the behaviour of a variable compressor volume in very different performance conditions. It is able to calculate; the instantaneous pressure and temperature variation in the cylinders, the instantaneous dynamics of the valves, the instantaneous mass flow rates through the valves, the compressor volume and the equilibrium temperature of the solid parts.; This model has been adapted to a 7 cylinder compressor, comparing the experimental results obtained in a test campaign with the ones calculated by the model.; The performed comparison shows that the compressor model is able to predict the volumetric efficiency within a ±5% and the outlet temperature within ±5K. This proves the model to be a helpful tool for compressor design and optimisation.