Oil Cooler Research Articles

A comparison study on thermal performance enhancement of corrugated oil cooler with internal turbulators – Numerical and experimental approach

Oil coolers play an important role in dissipating excess heat from engine oil to surroundings. In this work, performance study of an oil cooler with internal turbulators of dimple and offset type is performed using numerical approach and compared with experimental results for validation. In numerical approach, oil cooler with turbulators are numerically modeled using Conjugate Heat Transfer (CHT) approach to solve for heat transfer characteristics. Turbulence physics modeling is done using Reynolds Averaged Navier Stokes equations (RANS) through realizable k-epsilon model with standard wall function. The air side Heat Transfer Coefficient (HTC) estimation is done with CHT model using one corrugation, as the air flow in fins is periodic. In experimental study, Required Inlet Temperature Difference (ITD), Oil Flow Rate, Air Flow Rate is maintained, measurements are recorded to create performance data matrix with combinations of various operating data points for air and oil sides respectively. Numerical results are compared with experimental results obtained; Deviation for heat rejection of oil-cooler with dimple turbulator fall in range of ±7%, offset turbulator fall in the range of −2.0 to 9.4%. Numerical data shows that the thermal performance of offset type is better than dimple type by 10–13.5%, while the test data depicts that performance of oil-cooler with offset turbulator is high by 12–19% than dimple type and thereby proving its performance superiority. In offset turbulator additional turbulent scales of the offset length scale range are generated, these additional scales are evident by increasing the Turbulent Kinetic Energy (TKE) of 46–51% than dimple turbulator from numerical study. Thus, for same plate and fin, oil-cooler with offset turbulator has better thermal performance than oil cooler with dimple turbulator.

OPTIMIZATION OF THE DEVELOPED OUTER SURFACE OF AN INDUSTRIAL OIL COOLER

Heat removal from the working liquid of hydraulic systems requires the use of heat exchange devices - oil coolers with their geometry directly affecting their efficiency. This paper considers the issues of statement and implementation of the numerical experiment to solve the optimization problem for the industrial oil design.

Analisis Pengaruh Modifikasi Penukar Panas Terhadap Efisiensi Pendinginan Oli Gearbox Separator pada Pabrik Semen

Inside the cement factory, there is a finish mill which functions for the mixing process between clinker and gypsum to be used as cement. In that section there is a separator that functions to separate the finished cement and cement that still requires a re-milling process. In the separator there is a separator rotor which has a role to separate cement according to the size of the granulation so that those with standard sizes can be easily pushed by the circulating air fan and brought to the cement silo. The separator rotor is rotated by a motor which is passed by the gearbox as the transmission system. In order for the gearbox to work optimally, oil with certain temperature conditions is needed. Over time, the oil will become hot and cannot work effectively, so an oil cooling system is installed in this system. The oil cooler is a heat exchanger with water cooling fluid. This study aims to apply the NTU (Number of Transfer Units) method, in order to obtain an efficient and suitable heat exchanger working system as an oil cooler. The results obtained are an increase in efficiency of 2.74% from 35% to 37.74%.

Modelling and experimental investigation of temperature field during fly-cutting of KDP crystals

KDP crystal is the primary nonlinear crystal for making core components of inertial confinement fusion and laser frequency doublings. However, as a soft-brittle material, KDP crystal is difficult to machine due to its easy deliquescence, high brittleness, and sensitive to high temperature. A theoretical model of temperature field during fly-cutting of KDP crystals assisted by coolant lubrication was established based on cutting-heat generation theory and thermal transmission theory. This model considered the thermal exchange between the air and work material, the thermal exchange between the fluid and work material, and anisotropy of KDP crystals. The predicted results of the model indicated that oil coolant could effectively increase the thermal diffusivity and decrease the friction coefficient between cutting tools and work materials, thus decreasing the cutting temperature during the fly-cutting process. The highest cutting temperature in coolant lubrication cutting decrease by 9.42–36.70% compared with that in dry cutting. The fly-cutting experiments of KDP crystals assisted by coolant lubrication were performed to verify the model, which indicated that experimental results agreed well with predicted temperatures and the average error of the highest temperature was approximately 7.78%. Both simulated and experimental results indicated that increasing feed speed and cutting depth or decreasing the cutting speed would result in the obvious increase of the highest cutting temperature.

Experimental and Numerical Analysis of the Transient Behavior of the Oil Decongealing Process in an Aero Fuel-Cooled Oil Cooler Under Low-Temperature Conditions

Abstract The fuel-cooled oil cooler (FCOC) in the lubrication circuit plays a critical role in the aero gas-turbine engine's aerothermal management. However, the low temperature of the operating environment can congeal the oil and reduce the FCOC efficiency. The oil bypass valve (OBV) installed on the FCOC prevents pressure loss. Its failure may cause overheating, requiring preemptive performance prediction. Experimental and numerical analyses were used to evaluate the cooler's decongealing performance under typical boundary conditions of pressure and temperature, OBV configurations, and rerouting of feed oil and fuel flow paths. The temporal variation of oil and fuel mass flow rates, temperature, and pressure of the feed oil and fuel provided an insight into the decongealing process and duration. The experimental data were used to develop a one-dimensional (1D) flow and thermal network analysis model based on the effectiveness (ε)-number of thermal units (NTU) method to predict the transient oil decongealing performance of the FCOC. The customized commercial code predicted the decongealing phenomena using empirical correlations with property correction schemes, showing good agreement with the experiment. The findings revealed various ways to enhance the decongealing performance of the FCOC. The study results showed that the operating boundary conditions, OBV location and status, and flow arrangements affect decongealing behavior and time. The present numerical model provides results quickly and can effectively predict experimentally costly and complicated cases. The attempted estimates of steady heat rejection and detailed methodology could guide future studies and practical applications.

HEAT EXCHANGER DESIGN OPTIMISATION

In this paper, an optimized model of Shell and Tube Parallel Flow Heat Exchanger of water and oil type is proposed using C++ programming language. Shell and tube heat exchangers are of special importance in boilers, oil coolers, condensers, pre-heaters etc. They are also used in high pressure operations, refrigeration and air conditioning industry and process applications. In this paper, a number of practical cases of shell and tube heat exchangers are taken and the analysis of thermal and constructional design of every case is done. The optimised design is obtained by minimising the pressure drop by maximising the heat exchanger area to reduce pumping and running cost. Also considering that large sizes lead to increased capital cost, heat exchanger area is also optimised to overcome this problem. Effect of design parameters on pressure drop and heat exchanger area is also explained.

Discussion and analysis on problems of lube oil cooler and the oil cooler three way valve of a thermal power unit

Lube oil cooler is an important heat exchange equipment to provide suitable oil temperature for steam turbine unit. Its reliability is directly related to the normal operation of the unit. Combined with the system commissioning work, this paper finds out the problems existing in the lube oil cooler body and the oil cooler three way valve, and puts forward several improvement and optimization schemes, so as to improve the operation status of the equipment, improve the reliability of the system, and also facilitate the maintenance of the equipment, which provides a design reference for ensuring the safe and economic operation of the unit.

Thermodynamic assessment and optimization of the influences of the steam-assisted turbocharging and organic Rankine cycle on the overall performance of a diesel engine-based cogeneration integrated with a reverse osmosis desalination unit

Waste heat recovery (WHR) of internal combustion engines (ICEs) is a subject of study for researchers concerned with energy conservation. For this purpose, various bottoming cycles, along with the influences of Steam-Assisted Turbocharger (SAT) on diesel engines' performances, have sufficiently been investigated. In this paper, a cogeneration system powered by a steam-assisted turbocharged marine Diesel engine and an organic Rankine cycle (ORC) is thermodynamically evaluated. Seawater is desalinated by a Reverse-Osmosis (RO) module to provide freshwater for heating units and engine's cooling jacket. Exergy analysis reveals that the condenser, the RO module, the heat exchanger 1, and the oil cooler are the devices with the lowest exergy efficiencies. Furthermore, the genetic algorithm is used to optimize the system parameters and determine the best combination of the proposed system. Results indicate that the combination of SAT with other components can negatively affect the cogeneration system's overall efficiency. On the optimal state, the system exhibits cogeneration energy and exergy efficiencies of 82.82% and 54.10%, respectively, being 2.18 and 1.54 times higher than the sole engine. The optimized system offers a net electrical power of 668 kW and a heating capacity of 646.3 kW through supplying process steam and domestic hot water (DHW).

Experimental Study of Heat Transfer in Concentric Triple Pipe Heat Exchanger

Heat exchangers are devices which are used to transfer the thermal energy between two or more fluids. They are used in various industries for space heating, air conditioning and chemical processing. Some heat exchangers which are experienced in our daily lives include pasteurization, radiators and oil coolers in automobiles Heat exchangers have been divided in several ways, based on its flow direction which are parallel or counter flow, types of construction of the heat exchanger like tubular or plate heat exchanger, the ways of contact between the fluids i.e. direct or indirect.The heat exchangers performance is usually depending upon the physical characteristics of the fluid and the material. When a concentric tube is added in the intermediate space of a double pipe heat exchanger, we obtain a triple pipe heat exchanger, we obtain a triple pipe heat exchanger. The performance of the triple is better than the double pipe, as it provides better heat transfer efficiencies. Basically, the additional pipe improves the heat transfer by providing an additional flow passage and a larger area for heat transfer area per unit length of the exchanger.

An experiment investigation of temperature control performance for machine tool oil coolers with hot-gas bypass temperature control scheme and inverter temperature control scheme

Following the machine tool with demands of high-speed, high-precision machining and multi-axis, the heat generation of machine tool will lead to thermo growth of spindle, thermal error, etc. Therefore, the machine tool oil cooler has been frequently adopted for thermal management of heat generation for machine tool. However, it will be quite challenging to develop high-precision machining without suitable temperature control scheme. And, the machine tool oil cooler with on-off control is difficult to control the oil temperature accurately. Therefore, in this paper, the machine tool oil cooler with hot-gas bypass temperature control scheme and inverter temperature control scheme based on the PID control logic have been proposed to solve the oil temperature control problem for machine tool oil cooler. Furthermore, the temperature control performance (i.e. thermo growth of spindle, oil temperature control accuracy, and EER) of hot-gas bypass temperature control scheme and inverter temperature control scheme has been compared by means of experiment. The experimental results shows that the inlet oil temperature control accuracy can be maintained ±0.2 °C during spindle operation by using the hot-gas bypass temperature control scheme (HGB cooler) and inverter temperature control scheme (INV cooler). Furthermore, the thermo growth of spindle of HGB cooler is about 14 % smaller than the INV cooler because of hot-gas bypass temperature control scheme with thermal compensation function. However, the total power consumption of HGB cooler is about 0.18 kW higher than the INV cooler. Hence, the energy efficiency ratio (EER) of INV cooler reveals about 10.9 % higher than the HGB cooler at steady state. Furthermore, when oil flow rate declined to about half, the temperature difference between initial and final steady state temperature of the spindle is increased around 94.3 %, and the thermo growth of spindle is increased 58.7 %.

Experimental investigation of cooling medium on submerged friction stir processed AZ31 magnesium alloy

Submerged Friction stir processing (SFSP) has become apparent as a technique to modify microstructure. It is used to generate refined grains, modify microstructure, achieve superplasticity, synthesize insitu composite and form intermetallic compounds. In this work, AZ31magnesium alloy is friction stir processed at different rotational and welding speed while submerged underwater, cooling oil and brine solution. The effects of different medium on tensile strength, percentage of elongation, hardness, average size of grains in submerged friction stir processed magnesium alloy samples are discussed and the final results are compared. This investigation produces evidence that submerged friction stir processing under coolant oil results in lower peak temperature. During SFSP, water cooling resulted in lower tensile strength when compared to brine solution and coolant oil.

An improved numerical analysis of the transient oil de-congealing process in a heat exchanger under low temperature conditions

In the present study, an improved heat exchanger model is proposed to efficiently analyze the cold oil removal process inside a fuel-cooled oil cooler. When exposed to low temperature condition, oil within a heat exchanger begins to congeal, preventing oil flow and causing loss of cooling. The conventional heat exchanger models, however, shows limits in reflecting the highly varying viscosity effects due to large temperature difference. To overcome this, the conventional porous media model was rewritten with the friction and Colburn j-factors that include the temperature dependent property variation. The property correction method by Shah and Sekulic [31] was added to enhance the prediction accuracy. Also, a relief valve model based on the porous media approximation is developed. The developed models were validated against the experimental data. Transient three-dimensional numerical simulations are carried out to analyze the effects of operating conditions on de-congealing phenomenon inside the FCOC.

Optimal Plate Heat Exchangers of Power Generation Systems

Plate heat exchangers are an effective type of heat exchange equipment and can be used in many power plants. The article analyzes the use of corrugated plate heat exchangers in a number of installations. Their optimization was done according to the economic criterion of optimality, taking into account capital investments and operating costs. The analysis of the plate heat exchangers uses as oil coolers (a number of loads with oil mass flow rates 10….250 kg/s) and water heaters (heat power 100…2000 kW) of steam turbine plants. It has been established that plate oil coolers are more economical than shell-and-tube ones. Also, the anti-icing system plate air heaters of gas turbine plants with a power of 1 to 20 MW considered. The air for the anti-icing system was taken after the compressor and was additionally heated by exhaust gases. It has been established that it is necessary to install an additional flue gas smoke exhauster for using plate heat exchangers. Air must be extracted after the compressor, otherwise, low air density leads to high hydraulic losses, which makes it impossible to use plate heaters. Optimum air velocities are in the range of 0.4…0.6 m/s, flue gas velocities are 4…6 m/s. The use of standard plate heat exchangers with corrugated plates is impractical for GTU powers above 5 MW. Optimization of plate regenerators of supercritical CO2 cycles with recompression for powers from 1 to 15 MW has been done. Optimum velocities of hot CO2 are about 0.8 m/s, cold ones 0.3…0.5 m/s. The optimal sizes of plate heat exchangers are recommended for all of the above applications.

Optimized sorber bed heat and mass exchangers for sorption cooling systems

Low sorbent thermal diffusivity and off-the-shelf design of sorber beds have impeded the wide market adoption of sorption systems. In this study, graphite flakes are added to the sorbent to increase the thermal diffusivity and sorber beds are specifically designed and optimized for sorption systems. First, an analysis of variance is carried out to find the key parameters of sorber beds using the developed 2-D analytical models. It is shown that all components of the sorber bed, namely the sorbent, heat exchanger and heat transfer fluid, should be optimized simultaneously. Moreover, the specific cooling power (SCP) and coefficient of performance (COP) should be optimized simultaneously due to their conflicting trends. Thus, using the developed analytical models and multi-objective genetic algorithm, an optimization study is conducted. Based on the optimization results, two new sorber beds of finned-tube sorber bed heat and mass exchanger (F-HMX) and plate-fin sorber bed heat and mass exchanger (P-HMX) are designed, built, and tested in our custom-built two-sorber bed sorption test bed. The experimental results show that the present P-HMX can achieve an SCP of 1,005 W/kg sorbent, and a COP of 0.60 which are higher than the previously published results in the literature. Furthermore, the F-HMX design yields an SCP of 766 W/kg and a COP of 0.55. It is shown that the P-HMX, which is specifically designed and optimized for sorption cooling systems, provides up to 4.3 times higher SCP, and 3 times higher COP compared to an off-the-shelf heat exchanger, an engine oil cooler coated with a similar composite sorbent consisting of CaCl2, silica gel B150 and PVA. The present P-HMX has been tested under a wide range of operating conditions: i) desorption temperature (60–90 °C); ii) sorption and condenser temperatures (20–40 °C); iii) evaporator temperature (5–20 °C); and iv) cycle time (10–20 min). The SCP in the range of 320–1,230 W/kg and COP of 0.40–0.80 are measured in our test bed over the targeted operating conditions.

Numerical performance analysis of a novel shell-and-tube oil cooler with wire-wound and crescent baffles

Shell-and-tube oil coolers (STOC) are widely used in heat transfer of power systems. However, high-viscosity lubricants cause their oil-side heat transfer coefficients to be one order for magnitude lower than their water-side counterparts. Given this, a STOC with wire-wound (STOC-W) was designed to enhance the heat transfer of the oil cooler shell-side. The thermo-hydraulic performance of STOC-W is investigated by the numericalsimulation. According to the numerical calculation results of STOC-W, the STOC with wire-wound and crescent baffles (STOC-W-CB) was further proposed. The three factors (wire-winding angle, winding section shape, and baffles angle) that affect the heat transfer coefficient (HTC) of the STOC-W-CB were furtherly simulated and analyzed. The thermo-hydraulic performance of the STOC-W-CB and STOC with helical baffles (STOC-HB) were also compared. The results show that the structure of wire-wound and crescent baffles can effectively improve the shell-side heat transfer of the oil cooler. When Re is 201, the Performance Evaluation Criteria (PEC) of the STOC-W-CB is 2.2 times that of the bare tube cooler. The shell-side heat transfer coefficient of the STOC-W-CB are dramatically decreased with the increasing of the wire-winding angle. The best combination of the novel oil cooler is 30°-square wire winding with 10°-crescent baffles. When the Reynolds number is in the range of 100–350, the average heat transfer coefficient of STOC-W-CB is about 44% higher than that of STOC-HB.

The Proposition of an Automated Honing Cell with Advanced Monitoring

Honing of holes allows for small shape deviation and a low value of a roughness profile parameter, e.g., Ra parameter. The honing process heats the workpiece and raises its temperature. The increase in temperature causes thermal deformations of the honed holes. The article proposes the construction of a honing cell, containing in addition to CNC honing machine: thermographic camera, sound intensity meter, and software for collecting and analyzing data received during machining. It was proposed that the level of sound intensity obtained during honing could be monitored continuously and that the images from a thermographic camera could be analyzed on-line. These analyses would be aimed at supervising honing along with the on-line correction of machining parameters. In addition to the oil cooler, the machining cell may have an automatic selection of the grain trajectory shape, with specified value of the radii of curvature of the abrasive grain trajectories, according to the wall thickness of the honed workpiece, which will result in reducing the temperature generated during honing. Automated honing cell can mostly increase honing process efficiency. Simulations in FlexSim showed the possibility of increasing the efficiency of the honing process more than 20 times.

Research on heat transfer and pressure drop performance of plain plate fin-and-tube oil cooler

According to the characteristics of large number of sets and large size differences in the plain plate fin-and-tube oil cooler, a set of heat exchange units including a baffle is selected as the characteristic structure, and the heat transfer and pressure drop characteristics are numerically simulated and experimentally studied. The simulation results are compared with the experimental data to study the effects of changes in shell-side flow rate and plate-fin spacing on the heat transfer and pressure drop characteristics in the oil cooler. The results indicate that as the shell-side flow rate increases, both the heat transfer coefficient and pressure drop increase. When the shell-side flow rate is 1.6 m3/h, the heat transfer effect is the best; when the plate-fin spacing is 4 mm, the channel flow distribution is the most uniform, therefor the heat transfer effect is the best. The relationship curve between shell-side Nu number and Re number of the plain plate fin-and-tube oil cooler is obtained by fitting. It is used to explore the flow field and heat transfer characteristics inside the multi-layer small-spacing plain fin structure, which is instructive for optimizing its internal structure.

The Identification of Pre-Failure Conditions of Oil Coolers of NPP MCP by Operating Parameters

The article deals with the results of empirical modeling of the oil system of the main circulation pumps of a nuclear power plant, designed for oil supply to support bearings and their cooling. The empirical model extends the industrial monitoring platform with a sliding linear predictor to maintain the operational safety and operability of the MCP. The initial data for the predictor are the controlled parameters of the MCP.

Analisa Pengaruh Variasi Parameter Gurdi (Drilling) Dan Pendingin Terhadap Burr Formation Hasil Pemesinan Cnc Routermilling Pada Aluminium Sheet 1100

In the machining process, one of the things that cannot be released is the occurrence of burr formation or chip that sticks to the moment after the deduction process is carried out. To reduce burr formation is usually by determining good cutting parameters and given a cooling medium that functions to control the temperature during lubrication.This study aims to determine the burr formation on the 1100 aluminum sheet material using the machining method of milling raouter with the depth of feeding in accordance with the thickness of the workpiece. The spindle rotation used is 1200 rpm with a variation of the cutting tool eyes that is 4 mm, 6 mm, and 8 mm of the HSS tool brand and variations of the cooler namely air, coolant, oil. This research uses taguchi and ANOVA methods by measuring burr formation using USB microscope with 1200 x magnification. Then get the smallest burr formation value of 0.16819 mm with the parameter arrangement of the diameter of the drill bit 6, (f) 40 mm / minute, oil coolant. As for the Exit (outlet) the smallest burr formation of 0.27211 mm in the arrangement of the diameter of the tool diameter of the 4, (f) 50 mm / minute oil cooler.

Enhancement of heat transfer of heat exchangers using in transport by pulsating flow

The oil coolers are used in the hydraulic system of transport vehicles. In the shell and tube water oil coolers, oil is can be located on the tube side, water in the shell side. Different enhancement of heat transfer methods is used in oil coolers. The paper presents the results of a numerical study of the effect of asymmetric flow pulsations on the enhancement of heat transfer in a pipe for a highly viscous fluid with a Prandtl number Pr 293. The pipe length was 12 pipe diameters. The Reynolds number Re calculated from the inner diameter of the pipe was 100. The Strouhal number Sh was inside the range from 0.14 to 1.13. The amplitude of the pulsations of the flow had a reciprocating motion. The dimensionless relative amplitude of the pulsations was 1, 3, and 5. An increase in heat transfer was observed over the entire range of pulsation frequencies and amplitudes. The intensity of the pulsating flow significantly increases the heat transfer in the pipe. A comparison of the effectiveness of harmonical and asymmetric pulsations for enhancement of heat transfer was carried out. It is noted that the efficiency of asymmetric pulsations increases with increasing amplitude and frequency of pulsations. The maximum enhancement of heat transfer with asymmetric and harmonic pulsations was 2.03 and 1.93, respectively.