Mathematical Model of Unsteady Heat Transfer of Passenger Car With Heating System

Abstract

Purpose. The existing mathematical models of unsteady heat processes in a passenger car do not fully reflect the thermal processes, occurring in the car wits a heating system. In addition, unsteady heat processes are often studied in steady regime, when the heat fluxes and the parameters of the thermal circuit are constant and do not depend on time. In connection with the emergence of more effective technical solutions to the life support system there is a need for creating a new mathematical apparatus, which would allow taking into account these features and their influence on the course of unsteady heat processes throughout the travel time. The purpose of this work is to create a mathematical model of the heat regime of a passenger car with a heating system that takes into account the unsteady heat processes. Methodology. To achieve this task the author composed a system of differential equations, describing unsteady heat processes during the heating of a passenger car. For the solution of the composed system of equations, the author used the method of elementary balances. Findings. The paper presents the developed numerical algorithm and computer program for simulation of transitional heat processes in a locomotive traction passenger car, which allows taking into account the various constructive solutions of the life support system of passenger cars and to simulate unsteady heat processes at any stage of the trip. Originality. For the first time the author developed a mathematical model of heat processes in a car with a heating system, that unlike existing models, allows to investigate the unsteady heat engineering performance in the cabin of the car under different operating conditions and compare the work of various life support systems from the point of view their constructive solutions. Practical value. The work presented the developed mathematical model of the unsteady heat regime of the passenger car with a heating system to estimate the efficiency of unsteady, transitional temperature states in passenger cars, taking into account the design features of the heating system and the regulatory requirements. This allows the development and implementation of optimal technical characteristics of heating appliances and the construction of an algorithm for controlling their operation in accordance with operating conditions, taking into account the thermal inertia of the car in the transitional modes of heating, on the basis of mathematical modeling.

Controlling of Train’s Interior Heating System for Maximum Energy Efficiency

“…Performance of heating system design has been improved recently with revised theories and modelling tools, with research devoted mostly on two topics -macroscopic level studies of heat energy balance, especially under transient conditions (see [5,13,25]), investigation of thermal inertia of the air in the passenger compartment [26], and microscopic level studies of air velocities, temperature gradients by utilizing computerized fluid dynamic (CFD) simulations, with the latter acquiring more and more attention.…”

“…These traditions of modelling are transferred also to other rail-bound transport means -trams [20] and light rail [21]. It is interesting to note that even locomotive hauled closed-space passenger coaches, which have several compartments separated by wooden internal walls, are not treated as separate compartments but as one large compartment, introducing in the energy balance additional members reflecting the thermal inertia of the walls [5]. This is contrary for the example to automotive industry, where in the interior of Controlling of train's interior heating system for maximum energy efficiency 123. a passenger car, four different climatic zones are realized and calculation models accordingly reflect that, even without partition walls [17].…”