Charge Air Cooler Research Articles

Dependencies for determining heat transfer coefficients and air resistance for heat exchangers with tubular-plate heat exchange surface

Problem. The article analyzes existing generalized dependencies for determining convective heat transfer coefficients and air resistance coefficients for tubular-plate surfaces widely used in the production of modern charge air coolers and radiators. It is established that practical application of such dependencies, in some cases, is associated with significant errors revealed during experimental checks. Consequently, there is a need to adjust such dependencies for corridor bundles of flat-oval tubes with transverse grouped finning by flat fins. Goal. The aim of this study is to correct experimental dependencies for heat exchange and resistance. Numerical coefficients are adjusted on this basis, while the structure of dimensional dependencies remains unchanged. Simultaneously, the study is conducted for further improvement of the methodology for obtaining similar dependencies. Methodology. Adjustment of generalized dependencies for determining convective heat transfer coefficients and air resistance coefficients for tubular-plate heat exchange surfaces is carried out experimentally. Results. New dependencies are proposed for determining heat transfer coefficients and air resistance coefficients for tubular-plate heat exchange surfaces. Their accuracy and efficiency are investigated over a wide range of regimes. Originality and practical value. Unlike known dependencies of a similar nature, the proposed dependencies are provided in a single complex that should be used in modern heat exchanger calculation methods. It is established that the maximum error in determining air temperature according to the proposed dependence does not exceed 0.3 °C for the entire investigated range, and the error in determining aerodynamic resistance does not exceed 8 %, indicating high accuracy of modeling. Such accuracy ensures the possibility of applying the proposed dependencies for engineering calculations.

Особенности комплексного расчета эжекционной системы охлаждения наддувочного воздуха в дизеле

The expediency of increasing the density of fresh charge at the inlet to the cylinder of a diesel engine with a gas turbine boost by using an ejection cooling system after the compressor to circulate cooling air through the cooler is substantiated. The urgency of improving the cooling systems of the charge air is noted in the direction of reducing the cost of power for operation and simplifying the design of their elements. The functional and design features of the elements of the charge air ejection cooling system are considered. The incompleteness of studying the functioning of the ejector at the outlet for intensive circulation of cooling air through the cooler matrix when placing the ejector after the turbocharger turbine is noted. The sequence of calculation of the system in the form of a block diagram is proposed, including a diesel engine, a compressor and a turbocharger turbine, a charge air cooler and an ejector in the exhaust system. The main factors characterizing the relationship between the functional and geometric parameters of the system elements are considered. The features of the complex calculation of the ejection cooling system for charge air in a diesel engine using mathematical modeling of processes in various elements of the system to find reserves and compromise solutions to reduce the cost of power for its operation and increase its efficiency are reflected. The results of the complex calculation of the ejection cooling system of the charge air using numerical modeling are presented graphically in the form of dependences of the parameters of its elements on the degree of pressure reduction in the turbocharger turbine. The analysis of the results of the complex calculation shows that the maximum values of the degree of cooling, charge air density and effective diesel power are achieved at different degrees of pressure reduction in the turbine or ejector. In this regard, it is concluded that it is advisable to choose the required values of the degrees of pressure reduction in the turbine or ejector on a compromise basis when designing an ejection cooling system for charge air.

The journey to digitalization with the digital twin concept

The journey to digitalization with the digital twin concept Claus H. Ibsen and Bilal A. Qadri from Vestas aircoil A/S explore digital twins from their completed Horizon 2020 project InDEStruct, targeting a digital twin concept for their charge air coolers. In the Industry 4.0 proposal, the digital transformation of companies and the use of IoT (internet of things) explores digital twins. A digital twin is a virtual representation of a physical system that serves as the real-time digital surrogate, which provides indication of its engineering performance. Data is sent to the digital model from the physical product, with the purpose of the digital model being able to provide performance measures to optimize the product. Using digital twins, Vestas Aircoil A/S is currently engaged in a new project. It aims at developing cost-effective digital twin frameworks based on digital sensing units. The state-of-the-art sensing technology, computing technology, simulation acceleration and co-simulation-based digital twins used are provided by a project consortium consisting of industrial partners and academic partners.

RESEARCH OF A HIGH-EFFICIENCY CHARGE AIR COOLER

Currently, internal combustion engines have become widespread as sources of mechanical energy in many areas of human activity. It is the internal combustion engines that were and remain the most widespread in transport, where, as a rule, strict requirements are put forward for the mass-dimensional characteristics of the engines and the power plant as a whole. In order to meet these requirements, there is a constant increase in the level of forcing of the engines. For diesel engines, the most common technical measure that provides an increase in the level of engine forcing with almost unchanged weight and dimensional characteristics is an increase in supercharging pressure. However, as a result of air compression, its temperature increases, which is proportional to the degree of increase in air pressure in the compressor. An increase in air temperature causes a decrease in the mass charge of the cylinders, and therefore, a significant deterioration in the fuel combustion process. It also causes an increase in the level of maximum temperatures of the cycle, which in turn causes an increase in thermal loads and the rate of formation of nitrogen oxides in diesel cylinders. The above determines the urgency of the tasks of implementing effective charge air coolers in modern high-pressure transport diesel engines. This technical problem can be solved using air or liquid coolers. The article considers a liquid cooler, because compared to an air cooler, it can be made more compact, allows to achieve a much smaller length and volume of the intake tract, as well as to simplify the layout of the intake tract as part of the power plant as a whole, which is a priority for diesel engines. The article considers the influence of the design parameters of the supercharged air cooler on its overall characteristics and the hydraulic resistance of the supercharged air flowing through the cooler. Thus, the article provides data indicating the possibility of making a compact, highly efficient supercharged air cooler while maintaining its hydraulic resistance at an acceptable level by choosing rational parameters.

Features of measurement of charge air temperature at the diesel receiver inlet

The features of the temperature field of air in the cross section of the charge air cooler are considered. Based on the experimental data, an improved method for measuring the charge air temperature at the outlet of the cooler is developed. Keywords: diesel, turbocharging, charge air cooler, ecology, economic feasibility. mab5-5@yandex.ru, andrew_warsaw@mail.ru

Supercritical CO2 Power Cycle and Ejector Refrigeration Cycle for Marine Dual Fuel Engine Efficiency Enhancement by Utilizing Exhaust Gas and Charge Air Heat

Dual fuel engines with LNG as fuel have become a feasible solution for ship power units in the current situation, but their fuel efficiency needs to be further enhanced to meet the increasingly stringent emission requirements. This paper designs a dual-loop system, including a supercritical CO2 power cycle and a thermally driven ejector refrigeration cycle, for recovering the exhaust gas and charge air heat of a marine dual fuel engine. The models of the waste heat recovery system, the evaluation indicators of the combined system, and the genetic algorithm optimization program are developed. Compared to the standalone machine, the waste heat recovery system can improve by about 9.3% of the engine’s fuel efficiency. The performance analysis shows that the ejector contributes to the highest share of exergy destruction and accounts for approximate 53% of the refrigeration cycle. There are optimal values for the compressor inlet temperature of about 8.1 MPa and for the turbine inlet temperature of about 305 °C. Finally, after optimization, the specific fuel consumption, fuel efficiency, and CO2 emissions of the combined system are around 137.9 g/kWh, 53.3%, and 537.4 g/kWh, respectively. It provides a feasible solution in which the charge air cooler can be wholly replaced by the ejector refrigeration cycle.

On combustion instability induced by water condensation in a low-pressure exhaust gas recirculation system for spark-ignition engines

Water condensation in low-pressure exhaust gas recirculation systems is a concern because of a potential impact on components durability, but its implication into the operation of modern spark-ignition engines has not been investigated in detail. In this work, such aspects are evaluated by tests in a turbocharged multi-cylinder engine installed in a climatic test bench. First, a previously developed and validated zero-dimensional model is used to identify conditions where condensation is produced inside the water charge-air cooler, so that the compressor durability and operation is not affected. Then, different engine points are tested with a constant 25% of recirculated rate. Results show that combustion instability can increase up to 6% (absolute) due to droplets accumulation and release inside the water charge-air cooler, confirmed by an endoscope at the WCAC outlet . The evaporation of these droplets during the intake stroke causes charge overleaning in specific cycles, affecting combustion and inducing occasional misfires. Consequently, the fuel consumption and unburned hydrocarbons can be increased up to 4% and 30%, respectively, compared to the results achieved without condensation. The low speed and load condition was clearly the most affected by the sudden dilution given the lower in-cylinder temperatures. The combustion model shows that condensation formation and eventual overleaning phenomenon is increased if low or zero-carbon fuels such as natural gas, methanol, hydrogen or ammonia are used. Results showed an increased temperature for condensation compared to a traditional gasoline, around 10 ∘C for methane and methanol and 20 ∘C for hydrogen and ammonia.

Dynamic model of the temperature downstream to an indirect charge-air cooler considering heat losses to the environment

Thermal management plays an increasingly important role for internal combustion engines due to the high demands on the transient response of vehicles and the legal requirements for pollutants. In particular, the goal to reduce exhaust-gas raw emissions while optimizing fuel consumption can be supported with the help of on-demand temperature control. One strategy to meet the thermal requirements connected to this consists of model-based approaches. For an implementation of such methods on an automotive electronic control unit, a sufficiently high accuracy has to be ensured by the underlying model, alongside the fulfillment of the real-time operation demand. In this publication, we suggest two analytical modeling approaches for heat exchangers with poor thermal isolation with respect to the surrounding. Here we lay a special focus on the real-time capability of the given algorithm for an automotive on-board application. To this end, we utilize the Hammerstein method which allows to divide the overall physical system into a nonlinear stationary part and a dynamical linear one. The former are based on the well-known concept for the dimensionless temperature change of heat exchangers, where we generalize this approach in order to take account of the heat-losses to the surrounding. We demonstrate our model for an indirect charge-air cooler in an internal combustion engine. For both models we find excellent accuracy, with an overall mean-absolute error of 1.23 K and 1.33 K respectively, when compared to experimental data sets containing measurements from the Worldwide harmonized Light Duty Test Procedure.

A model based investigation of evaporative cooling for polymer electrolyte fuel cells – System level analysis

Evaporative cooling is a promising concept to reduce the fuel cell system volume and mass significantly. This paper investigates the interactions between the fuel cell stack and the balance of plant in an evaporatively cooled polymer electrolyte fuel cell system (PEFCS). For this, a zero-dimensional PEFCS model, comprising the fuel cell stack, air compressor, charge air cooler, humidifier, hydrogen recirculation blower, condensing radiator and water separator has been developed and analyzed. Two evaporative cooling system architectures are compared to conventional, liquid cooling. Optimal operating conditions are determined by a numerical optimization of the net system power output. Main results show that evaporative cooling works on the system level over a wide range of operating conditions. The optimum system power and highest efficiencies are achieved at high temperatures (80–90 °C), low pressure (125–150 kPa) and a corresponding cathode stoichiometry between 1.5 and 3, allowing for a closed water loop at the same time. The air compressor shows an increased power demand, compared to conventional cooling and the exhaust gas condenser is identified as the one critical component for evaporative cooling. Its performance is key to an efficient operation and closed water loop at all ambient conditions.

Numerical modeling and experimental validation of heat and mass transfer inside charge air coolers with water condensation

A numerical model was developed for predicting the heat and mass transfer during condensation within a charge air cooler under different operating conditions. Numerical modeling of the charge air cooler was performed in a commercial CFD software with the condensation model implemented as a User Code. The semi-theoretical condensation model is based on the most common film condensation models and predicts the local condensation rate and the mass of the accumulated condensate. The validation of the numerical model was carried out using an experimental setup designed especially for this purpose. The measured and calculated values of the condensation rate and the mass of the accumulated condensate are in good agreement: the numerical model predicts the measured condensation rate within a mean deviation of 9.9% and the measured mass of the accumulated condensate within a mean deviation of 11.2%.

Analysis of pollutant emissions and fuel consumption, during real driving cycles in different intake temperature scenarios

Current European vehicle homologation regulations are increasingly restrictive. Recently, World-wide light-duty test cycle (WLTC) and Real driving emissions (RDE) cycles have been introduced as type approval tests for new vehicles. This document studies the effect of intake temperature on pollutant emissions and fuel consumption of a Euro 6 Diesel engine when tested under WLTC and RDE. The tests have been performed by setting the temperature at the outlet of the water charge air cooler (WCAC) at 35°C and 20°C in different tests. To do that, the air-cooler was immersed in a temperature-controlled water bath. This temperature reduction can be produced due to an improvement in the WCAC in the same ambient temperature or also with the same WCAC in case of the ambient temperature is lower. All tests have been carried out in an engine test bench, eliminating the uncertainty involved on the road (driving mode, traffic, ambient temperature, etc.). Once the WLTC and RDE cycles were performed, carbon dioxide (CO2) and pollutant results were analyzed. Nitrogen oxides (NOX) emissions were considerably reduced when the engine intake temperature air was decreased, concretely a 7.1% in RDE and 11.63% in WLTC and the CO2 emissions were also cut down around 1%.

Study of customer correlation bench test spectrum of charge air cooler of semi-trailer truck

In this paper, the bench test spectrum of charge air cooler of Semi-trailer truck, which is the bench test method of Charge Air Cooler reliability durability, and has the correlation with customer, is studied. Affecting CAC B10 life, thermal mechanical fatigue, gas pulse pressure fatigue and vibration fatigue are the main failure modes on the market. According to the principle that the users’ damage is equal to the bench damage in the laboratory, the durability assessment test method of Charge Air Cooler on the bench in the laboratory is established. By collecting the fleet data of the user groups, the target driving path covering 95% of the actual use intensity of vehicle users is determined. The field load spectrum on the target driving path is collected, the fatigue damage is calculated and comparing it with the damage of the test bench in the laboratory, and the relevant bench test spectrum of the Charge Air Cooler of semi-trailer truck with B10 life is formulated. The practical application results show that this method can accurately predict the potential failures of the Charge Air Cooler of semi-trailer truck. And product development cycle is effectively shortened.

Multifidelity simulation of underhood thermal system for a bus engine

This study performs a combined 0-dimensional/3-dimensional modelling approach to investigate the fluid flow and heat transfer characteristics of bus thermal management systems. The 3-dimensional model is deployed to develop new correlations for the heat transfer coefficient (Colburn-j factor) and the friction factor (Fanning-f factor) at the air-side of the multi-louver radiator and charge-air cooler. The effect of the fan operation is also taken into account. The existing correlations in the literature developed for cars where the radiator and charge-air cooler are placed in the front section of the vehicle exposed to a uniform incoming air flow. While in buses, these components are placed at the vehicle rear section and in contact with a turbulent and non-uniform air flow, highlighting the need for development of new Colburn-j factor and Fanning-f factor for air flow within the louvered fins in these two components. The coefficients developed are incorporated into the 0-dimensional model to predict the thermal characteristics of the bus underhood for a range of operating conditions. The 0-dimensional model simulates the heat interaction of the multiple thermodynamic systems. Thus, a better understanding of the thermal management is achieved by investigating the energy distribution within the engine compartment and describing the performance of the thermal systems. The 0-dimensional/3-dimensional model is examined under the peak brake power condition. A coolant mass flow rate of 3.74 kg/s and fans speed of 4000 rpm are the most optimum results since the coolant’s temperature is decreased by 5 °C and the parasitic losses are kept at minimum.

Effectiveness of charge air coolers with various types of cooling sections

Sections of charge air coolers of different designs and their performance indicators are considered. Recommendations on the selection of cooling sections are given. The indicators of environmental friendliness of a complete diesel engine are given. Keywords: diesel, turbocharging, charge air cooler, environmental friendliness, effectiveness. mab5-5@yandex.ru, a.kostrygin@icd-tmh.ru

Assessment of the technical condition of intercoolers for turbocharged internal combustion engines

The presented work considers the analysis of methods and means for assessing the technical condition of charge air coolers in vehicles in operation. Metallographic studies of the fragments of samples, identified local sections of the heat exchanger, have been carried out. Various defects of the internal heat transfer surface, caused by the influence of operational factors, have been revealed. The article also touches upon the problem of imperfection of methods and means of instrumental control of the operating parameters of the heat exchange equipment of road transport. It is proposed to carry out diagnostics of the technical condition of heat exchangers at specialized stands equipped with an instrumentation and apparatus complex. The prospects of new developments in the field of diagnostic equipment for determining the operating characteristics of heat exchangers with the ability to measure the most important parameter - heat transfer are noted. An important addition, confirming the relevance of the chosen direction of research, is the substantiation of the value of the described developments not only as a tool for measuring the parameters of the state of heat exchangers, but also to solve the problem of predicting their residual resource. The results of the conducted research are presented. Using the method of physical modeling, an algorithm has been developed for diagnosing the technical condition of the charge air cooler in operation. Issues of provision with methods and means of diagnosing parameters of heat exchangers of vehicles in operation and repair are considered.

Experimental Investigation of the Pressure Drop during Water Condensation inside Charge Air Coolers

<div class="section abstract"><div class="htmlview paragraph">This paper investigates the pressure drop with and without condensation inside a charge air cooler. The background to this investigation is the fact that the stored condensate in charge air coolers can be torn into the combustion chamber during different driving states. This may result in misfiring or in the worst-case lead to an engine failure. In order to prevent or reduce the accumulated condensate inside charge air coolers, a better understanding of the detailed physics of this process is required. To this end, one single channel of the charge air side is investigated in detail by using an experimental setup that was built to reproduce the operating conditions leading to condensation. First, measurements of the pressure drop without condensation are conducted and a good agreement with experimental data of a comparable heat exchanger reported in Kays and London [<span class="xref">1</span>] is shown. In case of condensation it is observed that the accumulated condensate leads to an increase in pressure drop. An equilibrium state is established between the condensate formed and the one discharged from the charge air cooler, which leads to pressure fluctuations. Furthermore, the amount of the accumulated condensate in the charge air cooler is considered when determining the Fanning friction factor. It is shown that with this consideration the two-phase pressure drop can be described by the single-phase Blasius approach in the investigated operating range of the charge air cooler. The mean deviation of the measured data from the correlation amounts to about 3.8%.</div></div>

Effect of transverse flow in porous medium on heat exchanger simulation optimization

To improve the accuracy of heat exchanger computational fluid dynamics (CFD) simulations, the transverse resistance coefficient of the cold side and the hot side of the water-cooled charge air cooler (WCCAC) is calculated using the fin element method, and the influence of several common factors on the resistance coefficient of the fin element is analyzed. The transverse resistance coefficient obtained from the simulation of the fin element is substituted into the WCCAC model and compared with experimental data. It was found that the fin element method can simulate the flow field of the WCCAC accurately, and the simulation results were closer to the experimental curve compared with the empirical method. This study provides guidance for the optimal design of the heat exchanger and is helpful to shorten the development time and to save costs.

An experimental analysis of acoustic input impedance of a narrow pipe with low Mach number flow and thermal gradient.

In this paper, the normalized acoustic input impedance of a narrow pipe with a strong axially non-homogeneous thermal profile subjected to low Mach number flow of up to 0.03 M is studied. The analysis is done experimentally, using the two-microphone three-calibration technique and the results are compared with numerical simulations, using an industrial finite element package. The main application of this study is in the acoustic design of water-cooled charge-air coolers in internal combustion engines. The measurements are done on an effectively semi-infinite narrow pipe. It is shown that neglecting the flow effect in the calibration process of narrow pipes can significantly increase the measurement error. The results show that although the direct modification of the normalized acoustic input impedance due to low Mach number flow is negligible, the flow exerts an indirect but significant effect on this parameter by modifying the thermal gradient profile. Therefore, taking this effect into account can help to achieve an improved acoustical design of engine intake lines.

Engine Characteristics Analysis of Turbocharged Spark Ignition Engine with Water Injection Charge Air Cooling

This paper presents the effect of engine performance by water injection charged air cooling. Water was injected into the intake manifold with different flowrate in a turbocharged spark ignition engine. The simulation was done on a validated engine modelling using GT-Power simulation that was based on a 1.6L turbocharged CamPro CFE engine. Two injectors were used to inject the water into the intake manifold. The addition of water injection shows potential to improve the engine operation characteristics. Improvement of brake torque as much as 19% and brake power as much as 10% have proven that the charged air cooling has improved the turbocharged engine. In this this study, the charged air intake raises the air density in the combustion chamber and has improved the brake specific fuel consumption as much as 23%. With the introduction of water to the upstream of the engine operation, the cooling effect does assist the engine to improve.

Engine model for onboard marine engine failure simulation

The primary source of the power for marine industry comes from large two-stroke low-speed marine diesel engines. The more severe emission regulations are forcing the ship owners to use more efficient engines. The electronically controlled engines were introduced which comply with the needs. The electronically controlled engine requires more calibration effort and is mostly based on calibration from the testbed with some environmental condition corrections. In this paper, the physical engine model was introduced including AVL multi-zone combustion model and self-developed models for turbocharger, charge air cooler, injector and rail model. Typical engine failures were simulated. The demonstrated engine model was based on six-cylinder large two-stroke low-speed marine diesel engine and verified with the measurements from the engine testbed. The model calibration was done for the pressure traces and available mean value measurement for 40%, 60% and 100% of engine load. The results show 2–7% of relative deviation of the BMEP, 1–2% relative deviation for in-cylinder peak pressure and almost no deviation in scavenged air pressure. The model showed representative engine behavior and was used for studies on engine failure simulation. The presented engine model can be used for optimization and diagnostic purposes.