G0501102 Measurement of Convective Heat Transfer Coefficient at Low Flow Rate of Automotive Heat Exchanger

2015 ◽  
Vol 2015 (0) ◽  
pp. _G0501102--_G0501102-
Author(s):  
Daichi GOTO ◽  
Hideaki KUROSO ◽  
Hiroyuki HIRAHARA
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Flow Rate ◽  
Convective Heat Transfer Coefficient ◽  
Low Flow ◽  
Low Flow Rate

scholarly journals Experimental Study on a Pulsation-enhanced Heat Transfer Device

2020 ◽  
Vol 6 (4) ◽  
pp. 243-251
Author(s):  
Z. Liu ◽  
A. Levtsev ◽  
Y. Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Flow ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Pulsation Frequency ◽  
Enhanced Heat Transfer

The pulsation-enhanced heat transfer technology is introduced, and a volume coil heat exchanger is designed. A pulsation valve is installed at the heat exchanger outlet of the heat exchanger to pulsate the heat medium, and the same heat exchanger is subjected to pulsation and non-pulsation heat transfer tests. Based on the experiments, combined with the theory of pulsation-enhanced heat transfer technology, heat transfer capacity, heat flow, and convective heat transfer coefficient coefficients, the effective temperature difference, heat flow, and convective heat transfer coefficient of the heat exchanger at different pulse frequencies are analyzed. The relationship between the pulsation frequency of the heat transfer effect of the heat exchanger is obtained. The test results show that the heat exchanger has higher heat exchange efficiency when there is pulsation under the test conditions.

Heat Transfer Enhancement in Split and Recombine Flow Configurations: A Numerical and Experimental Study

2016 ◽  
Author(s):  
Mojtaba Jarrahi ◽  
Jean-Pierre Thermeau ◽  
Hassan Peerhossaini
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Working Fluid ◽  
Transfer Enhancement

Heat transfer enhancement in laminar regime by split and recombine (SAR) mechanism, based on the baker’s transformation, is investigated. Two different heat exchangers, called SAR1 and SAR2, are studied. Their geometries are inspired from the previous studies reported in the literature. The working fluid on both, shell and tube side, is water and the temperature on the shell side is kept constant. Experiments are carried out for the Reynolds number range 100<Re<3000 when the Prandtl number is between 4.5 and 7.5. The results show that the convective heat transfer coefficient in the first element of heat exchanger SAR1 is higher than that in the second one, i.e. SAR2. However, the variation in the convective heat transfer coefficient from the first to the third element along the heat exchanger SAR2 is less significant than that observed for SAR1. Moreover, SAR2 causes a higher pressure drop, especially when Re>1000, and provides a less uniform temperature field at the outlet.

Heat Transfer Analysis of Internally Grooved Copper Tube R404-A Evaporators

2012 ◽  
Author(s):  
Cenk Onan ◽  
Derya B. Ozkan ◽  
Levent Ceran
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Copper Tube ◽  
Tube Heat Exchanger ◽  
Grooved Tube

Internally grooved copper tubes are used extensively in HVAC applications, direct expansion batteries and air or water cooled heat exchangers. The advantage of internally grooved copper tubes in evaporator and condenser units is an increase in the refrigerant-side heat transfer coefficient. When an internally grooved tube heat exchanger and a smooth-tube heat exchanger with the same dimensions are compared, the overall heat transfer coefficient and convective heat transfer coefficient are found to increase in different ratios. In addition to this difference, the refrigerant side pressure is found to be a function of the groove geometry, pitch space and choice of refrigerant. In this study, which is different from previous studies in the literature performed using single internally grooved tube condensers and evaporators, refrigerant R404-A is studied in the internally grooved tube evaporator. The heat transfer in the evaporator described here is 30% better than that observed in a conventional smooth-copper-tube evaporator. In the internally grooved tube, the internal surface area is 68% larger than that inside the smooth reference tube. As a result, the convective heat transfer coefficient inside the internally grooved tube is found to be lower than that in the smooth tube.

Numerical Investigation of Convective Heat Transfer on a Dynamic Wall Heat Exchanger With Varying Amplitude and Frequency

2020 ◽  
Author(s):  
Md. Habibur Rahman ◽  
Emdadul Haque Chowdhury ◽  
Didarul Ahasan Redwan ◽  
Hasib Ahmed Prince ◽  
M. Ruhul Amin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Mass Flow Rate ◽  
Convective Heat ◽  
Mass Flow ◽  
Flow Rate ◽  
Convective Heat Transfer Coefficient ◽  
Liquid Temperature

Abstract The current work aims to investigate the thermo-hydraulic performances of a dynamic wall heat exchanger by varying amplitude and frequency of the oscillating waveform. The lower wall of the channel is exposed to constant heat flux, the upper insulating wall is deforming in a sinusoidal waveform, and water is taken as the working fluid. The governing partial differential equations are solved by using the Arbitrary Lagrangian-Eulerian finite element method. The study has been performed in the transient regime for up to 1.0 second. At first the effects of frequency variation over the average mass flow rate, convective heat transfer coefficient, and the average liquid temperature have been observed for a particular amplitude of the dynamic wall. It has been found that the mass flow rate of water increases linearly with increasing frequency. Convective heat transfer coefficient decreases with increasing frequency up to 50 Hz, then starts to increase notably. Interestingly, the fluctuating average liquid temperature decreases and reaches a steady-state faster with increasing frequency. To explore the effect of amplitude over heat transfer characteristics, the amplitude ratio of the sinusoidal wave is varied maintaining a constant frequency of oscillation. It has been observed that with increasing amplitude, both mass flow rate and convective heat transfer coefficient increase exponentially. Increasing amplitude ratio from 0.5 to 0.9 results in an increment in the convective heat transfer coefficient by about 5 times. Although, the average liquid temperature decreases and reaches a steady state faster with increasing amplitude, initially the peak temperature of the water is recorded for the highest amplitude.

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