Deposits, derived primarily from the fuel but with some contribution from the oil are formed inside the combustion chamber of a spark-ignition engine with use. The growth of combustion chamber deposits (CCD) is a dynamic and, to an extent, reversible process which at any given time reflects the balance between the formation and removal processes. Engine surface temperature is the most important parameter that affects their formation and changes in engine operation which tend to increase surface temperature, reduce deposit growth. At a fixed temperature, less volatile fuels tend to form more deposits than more volatile fuels. Some detergent additive packages tend to increase CCD levels. CCD reduce the heat lost to the coolant and increase charge temperature thereby increasing flame propagation rates but reducing volumetric efficiency; they might also affect the final phase of combustion by as yet undefined chemical means. This is reflected as an increase in octane requirement and NOx and a reduction in maximum power but an improvement in fuel economy and a reduction in CO2 emissions. They might also lead to higher HC emissions but not necessarily always since there might be competing mechanisms which come into play. CCD effect on CO emissions is not clearly established. They can also cause other interference problems like carbon rap. It is not known to what extent engine performance is affected by small changes in CCD levels. There is a large variation in deposit growth and its response to changes in fuel, additives and engine operating conditions across the combustion chamber and between different engines. Similarly, the performance of different engines will be affected to different extents by the deposits. While assessing the effects of different fuels or additives on engine performance and emissions through their effects on CCD, the simultaneous effects on other aspects such as inlet valve deposits which might have their own effects on engine operation, should also be considered. The paper reviews the literature on these topics.

Combustion Chamber Deposits in Spark-Ignition Engines: A Literature Review

Modeling the Spark Ignition Engine Warm-Up Process to Predict Component Temperatures and Hydrocarbon Emissions

Engine Thermal Management with Electric Cooling Pump

With the increasing demands for vehicle dynamic performance, economy, safety and comfort, and with ever stricter laws concerning energy conservation and emissions, vehicle power systems are becoming much more complex. To pursue high efficiency and light weight in automobile design, the power system and its vehicle integrated thermal management (VITM) system have attracted widespread attention as the major components of modern vehicle technology. Regarding the internal combustion engine vehicle (ICEV), its integrated thermal management (ITM) mainly contains internal combustion engine (ICE) cooling, turbo-charged cooling, exhaust gas recirculation (EGR) cooling, lubrication cooling and air conditioning (AC) or heat pump (HP). As for electric vehicles (EVs), the ITM mainly includes battery cooling/preheating, electric machines (EM) cooling and AC or HP. With the rational effective and comprehensive control over the mentioned dynamic devices and thermal components, the modern VITM can realize collaborative optimization of multiple thermodynamic processes from the aspect of system integration. Furthermore, the computer-aided calculation and numerical simulation have been the significant design methods, especially for complex VITM. The 1D programming can correlate multi-thermal components and the 3D simulating can develop structuralized and modularized design. Additionally, co-simulations can virtualize simulation of various thermo-hydraulic behaviors under the vehicle transient operational conditions. This article reviews relevant researching work and current advances in the ever broadening field of modern vehicle thermal management (VTM). Based on the systematic summaries of the design methods and applications of ITM, future tasks and proposals are presented. This article aims to promote innovation of ITM, strengthen the precise control and the performance predictable ability, furthermore, to enhance the level of research and development (R&D).

https://www.mdpi.com/1996-1073/10/10/1636/pdf

Advances in Integrated Vehicle Thermal Management and Numerical Simulation

Experimental study on the heat transfer characteristics of subcooled flow boiling with cast iron heating surface

The influence on cylinder head temperatures of parameters such as cylinder head material, coolant composition, pressure, temperature and velocity was investigated. Each of these parameters was systematically varied and its influence on combustion chamber wall temperature measured. Good agreement is shown between the measured values and corresponding predictions from a heat transfer model incorporating forced-convective, sub-cooled, nucleate boiling. The results suggest that nucleate boiling can play an important role in the transfer of heat from cylinder head to coolant.

D Harris

Papers

Factors Influencing Combustion Chamber Wall Temperatures in a Liquid-Cooled, Automotive, Spark-Ignition Engine: