E3S Web Conf.
Volume 207, 202025th Scientific Conference on Power Engineering and Power Machines (PEPM’2020)
|Number of page(s)||12|
|Section||Thermal Equipment, Heat and Mass Transfer Processes|
|Published online||18 November 2020|
Heat transfer performance of R1234yf for convective boiling in horizontal micro-fin and smooth tubes
1 Ho Chi Minh City University of Technology (HCMUT), 268 Ly Thuong Kiet Street, District 10 Ho Chi Minh City, Vietnam
2 Vietnam National University Ho Chi Minh City, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Vietnam
3 Technical University of Sofia, Power Engineering and Power Machines Department, 8 Kliment Ohridski Blvd., 1000 Sofia, Bulgaria
* Corresponding author: email@example.com
This study analyses the performance of heat transfer process which occurs in the convective boiling of Hydro fluoro Olefin (HFO) refrigerant, R1234yf, in horizontal tube. Heat transfer and pressure drop of R1234yf are analyzed and computed at the same working conditions on the same size of outer diameter of tube do = 9.52 mm with difference of inner surface, one is a smooth surface and microfin for other. The flow pattern maps were built at 5°C saturation temperature with 8.62 kW/m2 of heat flux, it is presented that flow pattern of helix flow occurs at very low mass flux and low quality, while at that condition on smooth tube the flow is still stratified wavy flow. The comparison of heat transfer performance between microfin and smooth tube would be evaluated on enhancement factor E, penalty factor P and efficiency index I. With the mass flux on the range G = 111 -- 333 kg/m2s for 5°C boiling temperature, the results show that, average value of E is 2.18; 1.45 of P and 1.54 of I. One more impressing thing is that, at the quality “x” larger than 0.8, the dryout phenomenon takes place on smooth tubes while microfin tubes do not have this phenomenon.
© The Authors, published by EDP Sciences, 2020
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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