BACKGROUND: The microclimate in the bus cabin is of great importance in terms of both safety and comfort. The main parameters of the microclimate are temperature, humidity, dustiness and gassiness of the air, air exchange, the temperature of the elements of the interior surfaces and thermal radiation. AIMS: The article presents the results of calculating the heat loss in the air environment of the bus cabin using a mathematical model and experimental method. METHODS: The influence of different features of vehicle interior and exterior topology on the heat losses through the doors was estimated. The estimation of heat losses was performed using the ANSYS Fluent software package. The final result is to obtain the heat loss characteristics as a time-domain function. A field experiment was carried out to verify the obtained results. RESULTS: A set of numerical values and graphic characteristics giving an idea of the heat losses through the open doors of the bus cabin are presented. CONCLUSIONS: Due to the developed calculation method of determining the heat losses of the air environment, numerical values and graphical characteristics of the amount and intensity of time-dependent heat losses were obtained. The obtained results were verified experimentally. The study showed that the simulation in ANSYS Fluent and the field experiment have a discrepancy due to high values of the time constant of temperature sensors. In order to obtain the most accurate results, it is necessary to carry out the experiment with a time interval greater than the time constant.
Operation of electric buses in the winter climatic conditions of Russia is associated with the need to maintain positive temperatures of battery cells of the traction battery, taking into account the maximum available energy at battery temperature plus 20 ... 25 ° C. When operating battery cells that have negative temperatures, the energy of the batteries decreases by 20 ... 25%. The average temperature in the central part of Russia ranges from minus 18 ° C to plus 25 ° C. To ensure the battery operation in the above-mentioned temperature ranges, a thermostating system is installed. Depending on the operating conditions, these systems are performed both liquid and air. For air heating and cooling of the battery, a self-contained air heater is used as a heat source: a generator of heated air gases, and for cooling - supply and exhaust fans. Heated air passes through the collector from the auxiliary heater to the inlet ventilation holes. The geometric shape of the collector affects the flow rates of the air streams blown from the four outlets. Uneven consumption causes improper heating of the battery, which in turn leads to a charge imbalance between the individual battery packs and a decrease in battery capacity. The objective of the study is to determine the geometric shape of the air manifold, which provides equal heat flow through the outlet openings. The solution of this problem was performed by iterative calculations of air flows in various geometric forms of the collector in ANSYS CFX software. The results of calculation of air collectors intended for heating and ventilation of electric bus power batteries are presented in the article. The optimal shape, which ensures an equal flow of heat energy through the outlet holes, is determined.
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