Abstract
Some of the common commuter vehicles in some African countries including Nigeria are designed in such a way that significant amount of heat from the engine section infiltrate into the overcrowded and poorly ventilated passenger segment. A mathematical model is developed to simulate the thermal performance of the passenger segment in relation to occupants‟ thermal comfort. Two distinct cases are considered for two common passenger buses: (i) when the vehicles are motionless, and (ii) when they move at averagely steady speed. The effects of the number of passengers, total area of window openings, vehicle speed and ambient temperature on the temperature evolution within the segment are investigated. Fourth-order Runge-Kutta algorithm, implemented in MATLAB environment, is employed to solve the first-order differential equation model. Since the vehicles are without air conditioning systems, air change through the openings served as major avenue for heat removal. Results show that the temperature evolution in the segment, in both cases, increases progressively with time before attaining a steady state. The rate of increase is proportional to the rate of heat build-up which is mainly due to the heat from the engine segment and passenger metabolism in relation with the area of openings. The effects of the heat build up on the thermo-regulatory responses of the occupants are discussed.
Keywords: thermal performance, commuter vehicles, heat build-up, passenger segment, engine segment.