Automotive Science and Engineering
Volume:9 Issue: 1, Winter 2019

Adjustable throat-area expansion valves (ATAEV) are functioned as area regulator control units. In literatures, there are many expansion valves normally used in automotive air-conditioning systems, as regulator and electrical type valves. Nevertheless, a review study for such issue has not been introduced, according to the best of author knowledge. The present paper presents a review study for expansion valves used in air conditioning of automobiles. Different types of expansion valves are discussed including the working principles and the limitation of their working conditions.

In this research, a high-temperature Rankin cycle (HTRC) with two-stage pumping is presented and investigated. In this cycle, two different pressures and mass flow rates in the HTRC result in two advantages. First, the possibility of direct recovery from the engine block by working fluid of water, which is a low quality waste heat source, is created in a HTRC. Secondly, by doing this, the mean effective temperature of heat addition increases, and hence the efficiency of the Rankin cycle also improves.
The proposed cycle was examined with the thermodynamic model. The results showed that in a HTRC with a two-stage pumping with an increase of 8% in the mean effective temperature of heat addition, the cycle efficiency is slightly improved. Although the operational work obtained from the waste heat recovery from the engine cooling system was insignificant, the effect of the innovation on the recovery from the exhaust was significant. The innovation seems not economical for this low produced energy. However, it should be said that although the effect of the innovation on the increase of the recovery cycle efficiency is low, the changes that must be implemented in the system are also low.

In this paper, the acoustic analysis of noise has been done in automotive cabin at high speed. High-frequency noise sources are applied separately to the roof and floor panels as well as to the windshield of the vehicle, which has been investigated at both the driver's and rear passenger's head. The most important panels that have the most noise emission are specified. In order to analyze high frequencies, the Statistical Energy Analysis (SEA) method has been used; also, the Response Surface Methodology (RSM) has been used to obtain optimized panel in terms of minimally weighing and maximum noise reduction. The results show that the proposed panels with unconstrained rubber layer can reduce the cabin interior aerodynamically generated noise more than %6.

In order to improve the safety and longitudinal stability of a vehicle equipped with standard ABS system, this paper, analyzes the basic principles of vehicles stability and proposes a control strategy based on fuzzy adaptive control which will adjust PID gain parameters, using genetic algorithm. A linear three-degree-of-freedom (DOF) vehicle model was set up in Simulink and the stability test was conducted utilizing jointly a joint established simulation platform with CarSim.For controlling the brake length, traditional controllers have difficulty in guaranteeing performance and stability over a wide range of parameter changes and disturbances. Therefore, a 2 level controller by providing a modified Sliding Mode Control (SMC) will be used. Using this approach the flexibility increased and brake length and rotor temperatures decreases significantly. This results improvement of the vehicle’s stability and brakes fatigue lifespan.

In internal combustion engines, exhaust valve and its seat gain considerable temperature as the hot gases exit through them. So, the rate of heat transfer should be under control. In this study, the contact heat transfer coefficient has been estimated. An experimental study on an Air-Cooled internal combustion engine cylinder head has been considered. Using the measured temperatures of sensors located in specific locations of the exhaust valve and the seat and the method of linear extrapolation, the surface contact temperatures and constant and periodic contact heat transfer coefficient were calculated. Also, a sensitivity analysis has been done to study the effects of different parameters of contact pressure, contact frequency, heat flux and cooling air speed on thermal contact conductance. The results show that between the major four considered parameters, the thermal contact conductance is more sensitive to the contact pressure, then the contact frequency, heat flux and the cooling air speed are the most affecting parameters on thermal contact resistance.

The purpose of this study is to investigate the effect of radiation heat transfer on temperature distribution and heat flux to the walls of a diesel engine. A diffusion flame is modeled in a simple cylindrical geometry and boundary conditions are defined. A specific solver which can model the turbulent diffusion flame by considering radiation in participating media is used to solve the problem. The solver is verified using experimental data of a furnace. The results show that with considering radiation and non-gray effects in the model, the flame temperature is calculated higher than that with ignoring these effects (about 11% in problem considered in this study).