Thermal comfort of passengers in vehicle cabins is studied in the present work. Among plenty of physical effects which are influencing the thermal comfort of indoor occupants, the humidity factor is investigated. These physical effects can be counted in general as heating-/dehumidifying power of the Heating Ventilation Air- Conditioning (HVAC) system, thermal and solar radiation, heat conduction from solid materials, flow dynamics as well as humidity of the air. High fidelity simulations of thermal comfort of passengers demand strong coupled solution of all mentioned physical effects, i.e. flow dynamics, radiation, heat conduction as well as the equations taking into account thermo-physiological comfort of passengers. Such a system had been previously implemented and validated for dry air in the first part of the work. In the present study, the effect of air humidity on the thermal comfort values of passengers is investigated. In the present study, humid air is introduced in two different ways into the system. In the first method, percentage of water vapour in the mass flow rate from inlets is defined. In the second method, the cabin air is initialised and computed with a relative humidity. Later thermal comfort values of passengers are derived with respect to that relative humidity. The validation results show that thermal comfort values of passengers are influenced strongly by the presence of humidity (80% in that case) by utilising the second method. However, the first method of computation has no effect on the thermal comfort values. Various tests have been made both on generic cabin profiles as well as on real cabins. Although the dry air results agree well with the results of previously utilised tool at Daimler, the results of humid air differs strongly from that tool. The reason for that is obviously the difference in the computation of thermal comfort values between two codes in the case of air humidity. The new tool does not only offer as accurate results as that of previous simulation tool regarding thermal comfort values of passengers but also offers simplicity with respect to handling of this complex problem as it is an "all in one" program instead of coupling three different codes.
Thermal comfort simulations in the presence of humidity
2010
17 Seiten, 13 Bilder, 1 Tabelle, 6 Quellen
Aufsatz (Konferenz)
Englisch
Thermal comfort simulations on the presence of humidity
Kraftfahrwesen | 2010
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British Library Conference Proceedings | 1998
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