scholarly journals Measurement of Transient Fluid Temperature in the Heat Exchangers

10.5772/65686 ◽  
2017 ◽  
Author(s):  
Magdalena Jaremkiewicz
Keyword(s):  
Heat Exchangers ◽  
Fluid Temperature

scholarly journals Study of the Performance of a Novel Radiator with Three Inlets and One Outlet Based on Topology Optimization

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 594
Author(s):  
Tao Zhou ◽  
Bingchao Chen ◽  
Huanling Liu
Keyword(s):  
Topology Optimization ◽  
Heat Exchanger ◽  
Temperature Difference ◽  
Heat Exchangers ◽  
Exchange Capacity ◽  
Numerical Results ◽  
Fluid Temperature ◽  
Channel Depth ◽  
Goal Model ◽  
Flow And Heat Transfer

In recent years, in order to obtain a radiator with strong heat exchange capacity, researchers have proposed a lot of heat exchangers to improve heat exchange capacity significantly. However, the cooling abilities of heat exchangers designed by traditional design methods is limited even if the geometric parameters are optimized at the same time. However, using topology optimization to design heat exchangers can overcome this design limitation. Furthermore, researchers have used topology optimization theory to designed one-to-one and many-to-many inlet and outlet heat exchangers because it can effectively increase the heat dissipation rate. In particular, it can further decrease the hot-spot temperature for many-to-many inlet and outlet heat exchangers. Therefore, this article proposes novel heat exchangers with three inlets and one outlet designed by topology optimization to decrease the fluid temperature at the outlet. Subsequently, the effect of the channel depth on the heat exchanger design is also studied. The results show that the type of exchanger varies with the channel depth, and there exists a critical depth value for obtaining the minimum substrate temperature difference. Then, the flow and heat transfer performance of the heat exchangers are numerically investigated. The numerical results show that the heat exchanger derived by topology optimization with the minimum temperature difference as the goal (Model-2) is the best design for flow and heat transfer performance compared to other heat sink designs, including the heat exchanger derived by topology optimization having the average temperature as the goal (Model-1) and conventional straight channels (Model-3). The temperature difference of Model-1 can be reduced by 37.5%, and that of Model-2 can be decreased by 62.5% compared to Model-3. Compared with Model-3, the thermal resistance of Model-1 can be reduced by 21.86%, while that of Model-2 can be decreased by 47.99%. At room temperature, we carried out the forced convention experimental test for Model-2 to measure its physical parameters (temperature, pressure drop) to verify the numerical results. The error of the average wall temperature between experimental results and simulation results is within 2.6 K, while that of the fluid temperature between the experimental and simulation results is within 1.4 K, and the maximum deviation of the measured Nu and simulated Nu was less than 5%. This indicated that the numerical results agreed well with the experimental results.

Analytical Evaluation of Unsteady Thermal Hydraulic Characteristics in Shell and Tube Heat Exchangers

2006 ◽  
Author(s):  
Shiro Takahashi ◽  
Yuichi Narumi ◽  
Kiyoshi Ishihama ◽  
Akihito Yokoyama ◽  
Toyohiko Tsuge ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Nuclear Power ◽  
Power Plants ◽  
Tube Bundle ◽  
Fluid Temperature ◽  
Detached Eddy Simulation ◽  
Tube Heat Exchanger ◽  
Eddy Simulation ◽  
Safety And Reliability ◽  
Cfd Analyses

Many shell & tube heat exchangers are used in nuclear power plants. Unsteady thermal hydraulic phenomena have been studied in shell & tube heat exchangers to improve their safety and reliability and to extend their lifetime based on experience obtained from long periods of plant operation. We investigated unsteady flow in shell & tube heat exchangers by using computational fluid dynamics (CFD) analyses. The inlet flow on the shell side was separated and flow in several directions. A large part of the flow crossed over the tube bundle, and some parts of the flow took two circuitous roots (up and down) along the inner surface of the shell. Separated circuitous flows collided again where a baffle plate had been cut off. A pair of symmetric vortexes could be seen in that location. Some parts of the circuitous flow moved backwards into the tube bundle due to vortexes. These vortexes were unstable and changed their size and location. A pair of vortexes changed from symmetric to asymmetric. As a result, the direction of flow in the tube bundle near the vortexes changed continuously. Variations in vortexes simulated through CFD analyses could also be seen in tests on the actual size. Fluid temperature fluctuations around tubes were also evaluated through CFD analyses. Unsteady phenomena with changes from symmetric to asymmetric vortexes could be observed in the shell & tube heat exchanger and were simulated through CFD analyses with a detached eddy simulation (DES) turbulence model.

Vehicular Gas Turbine Periodic-Flow Heat Exchanger Solid and Fluid Temperature Distributions

1964 ◽  
Vol 86 (2) ◽  
pp. 121-126 ◽  
Author(s):  
J. R. Mondt
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
General Motors ◽  
Periodic Flow ◽  
Fluid Temperature ◽  
Transfer Coefficients ◽  
Temperature Distributions ◽  
Flow Heat

Design, fabrication, and operation experience with periodic-flow heat exchangers used in General Motors regenerative vehicular gas turbines has indicated that analysis techniques available in published reports are too restrictive for accurate performance and thermal distortion calculations. The design usefulness of previously published analyses is somewhat limited because fluid and metal temperature distributions are not part of the calculated results. These distributions are required for primary seal matching and core and structural thermal stress calculations. A nodal analysis has been accomplished at the General Motors Research Laboratories and a type of finite difference solution obtained for the periodic-flow heat exchanger. This solution can be used to study the effects of longitudinal thermal conduction, variable heat-transfer coefficients, finite rotation, and provides temperature distributions as functions of time and space for transient as well as “steady-state.” This has been checked both with available solutions for more simplified cases and some experimental measured results for periodic flow heat exchangers designed and built as part of the General Motors vehicular regenerative gas turbine program. A brief outline of the calculation procedures, program capabilities, and some calculated results is presented. This includes temperature distributions for periodic-flow heat-exchanger parameters encountered in the vehicular regenerator application.

Effect of the Circulation Flow Velocity in Ground Heat Exchangers on System Operation

2014 ◽  
Vol 580-583 ◽  
pp. 2457-2460
Author(s):  
Zi Shu Qi ◽  
Qing Gao ◽  
Yan Liu ◽  
Zhen Hai Gao ◽  
Li Bai
Keyword(s):  
Flow Velocity ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Engineering Practice ◽  
Fluid Temperature ◽  
Circulation Flow ◽  
Pump System ◽  
Heat Pump System ◽  
Computing Platform ◽  
Ground Heat Exchangers

The heat pump system by using earth energy is increasing very rapidly. In this paper, by studying the underground heat exchanger heat transfer mode, the computing platform for ground source heat pump system was established. Through a engineering case, the influence character of the circulation flow velocity in ground heat exchangers on the fluid temperature, the heat pump power consumption, and the length of system were analyzed, which provide an approach for system engineering design and operation prediction, and for the thermodynamic analysis of performance of system year by year and prospective study to guide the engineering practice.

scholarly journals Ground-Source Heat Pump Systems: The Effects of Variable Trench Separations and Pipe Configurations in Horizontal Ground Heat Exchangers

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3919
Author(s):  
Yu Zhou ◽  
Asal Bidarmaghz ◽  
Nikolas Makasis ◽  
Guillermo Narsilio
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Heat Pump ◽  
Heat Exchangers ◽  
Element Model ◽  
Fluid Temperature ◽  
Ground Source Heat Pump ◽  
Carrier Fluid ◽  
Ground Heat Exchangers ◽  
Ground Source

Ground-source heat pump systems are renewable and highly efficient HVAC systems that utilise the ground to exchange heat via ground heat exchangers (GHEs). This study developed a detailed 3D finite element model for horizontal GHEs by using COMSOL Multiphysics and validated it against a fully instrumented system under the loading conditions of rural industries in NSW, Australia. First, the yearly performance evaluation of the horizontal straight GHEs showed an adequate initial design under the unique loads. This study then evaluated the effects of variable trench separations, GHE configurations, and effective thermal conductivity. Different trench separations that varied between 1.2 and 3.5 m were selected and analysed while considering three different horizontal loop configurations, i.e., the horizontal straight, slinky, and dense slinky loop configurations. These configurations had the same length of pipe in one trench, and the first two had the same trench length as well. The results revealed that when the trench separation became smaller, there was a minor increasing trend (0.5 °C) in the carrier fluid temperature. As for the configuration, the dense slinky loop showed an average that was 1.5 °C lower than those of the horizontal straight and slinky loop (which were about the same). This indicates that, when land is limited, compromises on the trench separation should be made first in lieu of changes in the loop configuration. Lastly, the results showed that although the effective thermal conductivity had an impact on the carrier fluid temperature, this impact was much lower compared to that for the GHE configurations and trench separations.

scholarly journals Thermal Performance Analyses of Multiborehole Ground Heat Exchangers

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Wanjing Luo ◽  
Changfu Tang ◽  
Yin Feng ◽  
Pu Miao
Keyword(s):  
Thermal Performance ◽  
Heat Exchangers ◽  
Geothermal Energy ◽  
Greenhouse Gas Emission ◽  
Energy Resource ◽  
Thermal Dissipation ◽  
Uniform Heat Flux ◽  
Fluid Temperature ◽  
Cooling Mode ◽  
Ground Heat Exchangers

Geothermal energy known as a clean, renewable energy resource is widely available and reliable. Ground heat exchangers (GHEs) can assist the development of geothermal energy by reducing the capital cost and greenhouse gas emission. In this paper, a novel semianalytical method was developed to study the thermal performance of multiborehole ground heat exchangers (GHEs) with arbitrary configurations. By assuming a uniform inlet fluid temperature (UIFT), instead of uniform heat flux (UHF), the effects of thermal interference and the thermal performance difference between different boreholes can be examined. Simulation results indicate that the monthly average outlet fluid temperatures of GHEs will increase gradually while the annual cooling load of the GHEs is greater than the annual heating load. Besides, two mechanisms, the thermal dissipation and the heat storage effect, will determine the heat transfer underground, which can be further divided into four stages. Moreover, some boreholes will be malfunctioned; that is, boreholes can absorb heat from ground when the GHEs are under the cooling mode. However, as indicated by further investigations, this malfunction can be avoided by increasing borehole spacing.

The Transient Response of Heat Exchangers Having an Infinite Capacitance Rate Fluid

1970 ◽  
Vol 92 (2) ◽  
pp. 269-275 ◽  
Author(s):  
G. E. Myers ◽  
J. W. Mitchell ◽  
C. F. Lindeman
Keyword(s):  
Finite Difference ◽  
Transient Response ◽  
Heat Exchangers ◽  
Entire Range ◽  
Finite Difference Methods ◽  
Step Change ◽  
Fluid Temperature ◽  
Difference Methods

The transient response of heat exchangers to a step change in the temperature of the infinite capacitance rate fluid temperature is discussed. This work applies to condensers, evaporators, precoolers, and intercoolers. Analytical and finite difference methods are used to obtain solutions. The procedure for making useful hand calculations for the entire range of practical values of the parameters is presented.

Thermal Simulation of Plate-Fin Heat Exchangers

2013 ◽  
Vol 291-294 ◽  
pp. 1623-1626 ◽  
Author(s):  
Jin Jin Tian ◽  
Zhe Zhang ◽  
Yong Gang Guo
Keyword(s):  
Heat Conduction ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Temperature Response ◽  
Process Industry ◽  
Geometrical Parameters ◽  
Fluid Temperature ◽  
Recent Past ◽  
Plate Heat ◽  
Transfer Data

Plate-fin heat exchangers are playing an important role in the power and process industry in the recent past. Hence, it has become necessary to model their temperature response accurately. A new mathematical model of plate-fin heat exchanger is proposed, considering the heat conduction resistance along the fins and the separating plates. The effects of fin geometrical parameters and spacer thickness on the performances of the heat exchanger have been numerically calculated. It is found that the heat conduction resistance of fins has significant influence on the outlet fluid temperature variation. The analysis presented here suggests a better method of heat-transfer data analysis for plate heat exchangers.

Heat Transfer in Thin, Compact Heat Exchangers With Circular, Rectangular, or Pin-Fin Flow Passages

1992 ◽  
Vol 114 (2) ◽  
pp. 373-382 ◽  
Author(s):  
D. A. Olson
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Rectangular Channel ◽  
Fluid Temperature ◽  
Compact Heat Exchangers ◽  
Pin Fin

We have measured heat transfer and pressure drop of three thin, compact heat exchangers in helium gas at 3.5 MPa and higher, with Reynolds numbers of 450 to 36,000. The flow geometries for the three heat exchanger specimens were: circular tube, rectangular channel, and staggered pin fin with tapered pins. The specimens were heated radiatively at heat fluxes up to 77 W/cm2. Correlations were developed for the isothermal friction factor as a function of Reynolds number, and for the Nusselt number as a function of Reynolds number and the ratio of wall temperature to fluid temperature. The specimen with the pin fin internal geometry had significantly better heat transfer than the other specimens, but it also had higher pressure drop. For certain conditions of helium flow and heating, the temperature more than doubled from the inlet to the outlet of the specimens, producing large changes in gas velocity, density, viscosity, and thermal conductivity. These changes in properties did not affect the correlations for friction factor and Nusselt number in turbulent flow.

scholarly journals Use of the Low-Potential Heat for Heating Helium in Rocket-Carrier Tank Pressurisation Systems

2021 ◽  
Vol 24 (7) ◽  
pp. 9-19
Author(s):  
Igor Kravchenko ◽  
Yurii Mitikov ◽  
Yurii Torba ◽  
Mykhailo Vasin ◽  
Oleksandr Zhyrkov
Keyword(s):  
Heat Exchanger ◽  
Combustion Chamber ◽  
Heat Exchangers ◽  
Fuel Tank ◽  
Industrial Wastes ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Propulsion Systems ◽  
Rocket Carrier ◽  
First Time

The energy efficiency of new technical developments is a critical issue. It should be noted that today the focus in this issue has seen a major shift to the maximum use of renewable energy sources. The purpose of this research is to reduce the weight of helium heat exchangers of the fuel tank pressurisation systems in modern rocket propulsion systems that use fuel components like liquid oxygen and kerosene-type fuel. This is the first time that the question has been raised about the possibility and advisability of increasing the temperature of helium at the heat exchanger inlet without the use of additional resources. The paper addresses the use of the waste (“low-potential”) heat and ”industrial wastes” present in propulsion systems. Basic laws of complex heat exchange and the retrospective review of applicable heat exchanger structures are applied as a research methodology. Two sources of low-potential heat are identified that have been previously used in the rocket engine building in an inconsistent and piecemeal manner to obtain and heat the pressurisation working fluid. These are the rammedair pressurisation during the motion of the rocket carrier in the atmosphere, and the tank pressurisation as a result of boiling of the top layer of oxidiser which is on the saturation line. This is the first time that the advisability has been substantiated of increasing the temperature of the working fluid at the heat exchanger inlet, first of all due to the use of the low-potential heat. This is also the first time that unemployed sources of low-potential heat and “industrial wastes” are found in modern deep throttling propulsion systems. These are the high-boiling-point fuel in the tank, behind the highpressure pump, at the exit of the combustion chamber cooling duct, and also the fuel tank structures, and the engine plume. A possibility is proved, and an advisability demonstrated of their implementation to increase the efficiency of pressurisation system heat exchangers. This is the first time that the methodology of combustion chamber cooling analysis has been proposed to be adopted for the heating of heat exchanger by the engine plume. This is the first time that a classification of waste heat sources has been developed which can be used to increase the pressurisation working fluid temperature. The identified reserves help to increase the efficiency of the helium heat exchangers of the tank pressurisation systems in the propulsion systems

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