Internal Combustion Engine Heat Research Articles

Internal combustion engine heat release calculation using single-zone and CFD 3D numerical models

The present study deals with a comparative evaluation of a single-zone (SZ) thermodynamic model and a 3D computational fluid dynamics (CFD) model for heat release calculation in internal combustion engines. The first law, SZ, model is based on the first law of thermodynamics. This model is characterized by a very simplified modeling of the combustion phenomenon allowing for a great simplicity in the mathematical formulation and very low computational time. The CFD 3D models, instead, are able to solve the chemistry of the combustion process, the interaction between turbulence and flame propagation, the heat exchange with walls and the dissociation and re-association of chemical species. They provide a high spatial resolution of the combustion chamber as well. Nevertheless, the computation requirements of CFD models are enormously larger than the SZ techniques. However, the SZ model needs accurate experimental in-cylinder pressure data for initializing the heat release calculation. Therefore, the main objective of an SZ model is to evaluate the heat release, which is very difficult to measure in experiments, starting from the knowledge of the in-cylinder pressure data. Nevertheless, the great simplicity of the SZ numerical formulation has a margin of uncertainty which cannot be known a priori. The objective of this paper was, therefore, to evaluate the level of accuracy and reliability of the SZ model comparing the results with those obtained with a CFD 3D model. The CFD model was developed and validated using cooperative fuel research (CFR) engine experimental in-cylinder pressure data. The CFR engine was fueled with 2,2,4-trimethylpentane, at a rotational speed of 600 r/min, an equivalence ratio equal to 1 and a volumetric compression ratio of 5.8. The analysis demonstrates that, considering the simplicity and speed of the SZ model, the heat release calculation is sufficiently accurate and thus can be used for a first investigation of the combustion process.

Investigation and Development of the Thermal Preparation System of the Trailbuilder Machinery Hydraulic Actuator

It’s determined that the main part of trailbuilders operated in the North is the technology equipped by the hydraulic actuator. Further development of the northern territories will demand using of various means and ways machinery thermal preparation, and also the machinery of the northern fulfillment. On this basis problems in equipment operation are defined. One of the main is efficiency supplying of a hydraulic actuator. On the basis of the operating conditions’ analysis of trailbuilder hydraulic actuator operation it is determined, that under low negative temperatures the means of thermal preparation are necessary. The existing systems warm up only a hydraulic tank or warming up of the hydro equipment before the machinery operation is carried out under loading with intensive wears. Thus, with the purpose to raise the efficiency of thermal hydraulic actuator, operated far from stationary bases autonomous, energy saving, not expensive in creation and operation systems are necessary. In accordance with the analysis of means and ways of the thermal preparation of the hydraulic actuator and the thermal balance calculations of the (internal) combustion engine the system of the hydraulic actuator heating is offered and is being investigated. It contains a local hydraulic actuator warming up and the system of internal combustion engine heat utilization. Within research operation conditions of the local hydraulic actuator heating are viewed and determined, taking into account constructive changes to the local hydraulic actuator heating. Mathematical modelling of the heat technical process in the modernized hydraulic actuator is considered. As a result temperature changes of the heat-transfer and the hydraulic cylinder in time are determined. To check the theoretical researches and to define dependences on hydraulic actuator warming up, the experimental installation is made. It contains the measuring equipment, a small tank with the heat exchanger of the burnt gases of the internal combustion engine and the hydraulic cylinder with by-pass.

Analysis of Temperature Field of High Speed Diesel Engine Parts and their Structural Optimization

The analysis of structure and performance of internal combustion engine is presented in this paper from the following two aspects: the thermal load of I. C. Engine and the thermal efficiency of diesel engines. Firstly, the thermal load of key parts of I. C. Engine as well as the evaluation parameters of which are introduced briefly. Furthermore, based on the factors influencing the heat transfer process of internal combustion engine, the current research situation of internal combustion engine work process and heat balance for combustion chamber components, and the whole engine using numerical simulation method is described, while the coupled study of internal combustion engine components is developing trends of internal combustion engine heat balance study in the future.

Instantaneous Heat Flux Simulation of a Motored Reciprocating Engine: Unsteady Thermal Boundary Layer With Variable Turbulent Thermal Conductivity

Due to the inherently unsteady environment of reciprocating engines, unsteady thermal boundary layer modeling may improve the reliability of simulations of internal combustion engine heat transfer. Simulation of the unsteady thermal boundary layer was achieved in the present work based on an effective variable thermal conductivity from different turbulent Prandtl number and turbulent viscosity models. Experiments were also performed on a motored, single-cylinder spark-ignition engine. The unsteady energy equation approach furnishes a significant improvement in the simulation of the heat flux data relative to results from a representative instantaneous heat transfer correlation. The heat flux simulated using the unsteady model with one particular turbulent Prandtl number model agreed with measured heat flux in the wide open and fully closed throttle cases, with an error in peak values of about 6% and 35%, respectively.

Simulation of Instantaneous Heat Transfer in Spark Ignition Internal Combustion Engines: Unsteady Thermal Boundary Layer Modeling

Simulation of internal combustion engine heat transfer using low-dimensional thermodynamic modeling often relies on quasisteady heat transfer correlations. However, unsteady thermal boundary layer modeling could make a useful contribution because of the inherent unsteadiness of the internal combustion engine environment. Previous formulations of the unsteady energy equations for internal combustion engine thermal boundary layer modeling appear to imply that it is necessary to adopt the restrictive assumption that isentropic processes occur in the gas external to the thermal boundary layer. Such restrictions are not required and we have investigated if unsteady modeling can improve the simulation of crank-resolved heat transfer. A modest degree of success is reported for the present modeling, which relies on a constant effective turbulent thermal conductivity. Improvement in the unsteady thermal boundary layer simulations is expected in the future when the temporal and spatial variations in effective turbulent conductivity are correctly modeled.

Experimental investigation of heat losses in a ceramic coated diesel engine

Ever since the invention of this reliable workhorse of the automotive world, the quest for increasing the efficiency of an internal combustion engine has been going on. In recent times, much attention has been focused on achieving this goal by reducing energy lost to the coolant during the power stroke of the cycle. A cursory look at the internal combustion engine heat balance indicates that the input energy is divided into roughly three equal parts: energy converted to useful work, energy transferred to coolant and energy lost to exhaust. The reduction in, or the elimination of, in-cylinder heat transfer to either the coolant and/or the environment does not violate the second law of thermodynamics and, moreover, according to the first law, has the potential of producing more work. Added to this, another important advantage of the concept is the great reduction in parasitic losses due to elimination of cooling system, thus increasing the brake horsepower of the engine. The main purpose of this study is to evaluate the heat losses at different engine loads and speeds with and without ceramic-coated diesel engine. The results showed a reduction in heat losses to the coolant and an increase in exhaust energy at all load levels.