Numerical Simulation And Experimental Study Of Thermal Environment In The Highway Sleeper Bus Passenger Compartment

The poor thermal comfort of highway sleeper bus has became one of major problems severely affect on it' s existence and development, so the domestic bus manufacturers have taken various measures to improve it, and one of general measures adopted was equipped an air conditioning system with four ducts.In order to verified effectiveness of a four ducts air conditioning system equipped on a domestic-made luxurious highway sleeper bus, and checked the accuracy of numerical simulation results, an experimental study on air conditioning system' s air supply parameters and temperature distribution in the passenger compartment. Meanwhile, numerical simulations of passenger compartment' s thermal environment performed for the following two operating modes:· Maximum refrigeration· Uniform and isothermal air supplyIn the test program, hot-bulb anemometer and digital temperature meter were used to measure velocity and temperature of the air supply outlets respectively, a multi-channel data collector and thermal couple were used to measure temperature of measuring points above the sleepers. The results were used to evaluate the rationality of the designed air conditioning system and the thermal comfort of the passenger compartment, part of results were used as boundary conditions for the passenger compartment' s thermal environment numerical calculation. Meanwhile, the results of experimental measurement were also used to verify the accuracy of numerical calculation results.The numerical calculation of passenger compartment' s thermal environment as following: a proper simplification on the compartment model, the basic model method used for the air supply outlets' simplification. The density of air in the passenger compartment conformed to Boussinesq assumption, and participated in radiation heat transfer. Rectangular and unstructured hybrid grids, re-normalization group(RNG) k-ε turbulence model and discrete ordinates(DO) radiation model were adopt for the steady-state numerical calculation of air velocity filed and temperature filed, and obtained the distribution of air flow velocity and temperature in the passenger compartment.Read each measuring points' calculated temperature in the numerical calculation results, and compared with the results obtained from experimental measurement. The comparison show that: the calculated temperature close to experimental results on most of measuring points, and the trendline of calculated temperature show a good agreement with that of the experiment, which illustrate that the computational results are creditable and with a high accuracy.The results of numerical calculation in uniform and isothermal air supply operating mode prove that this operating mode is favorable to form uniform airflow organization and temperature distribution in the passenger compartment. Consequently, the design objective of highway sleeper bus air conditioning system' s ducts should be realize for uniform air supply rate, and use proper heat insulation measure, realize for uniform and isothermal air supply on air supply outlets.