{"title":"Experimental study on heat transfer enhancement in subcooled flow boiling under pressurized conditions","authors":"Rikiya Shiono, I. Kano","doi":"10.1299/jtst.2021jtst0033","DOIUrl":null,"url":null,"abstract":"the capacity of MC for heat flux values from 2.17 to 33.53 W/cm 2 at a system pressure of 100 kPa, an inlet degree of Abstract In this study, the cooling capabilities of flow boiling heat transfer aided by electrohydrodynamic (EHD) force and diamond-electrodeposited boiling surface is investigated in a micro-slit channel (MSC). The MSC uses a two-phase flow cooling system, in which an electric field is applied to a dielectric liquid using a slit electrode. To reduce the wall temperature below 60 °C and promote cooling in electronic devices, a dielectric liquid with a saturation temperature of 15 °C HCFO-1224yd (AGC, AMOLEA, CF 3 CF = CHCI) was selected as a working fluid. Moreover, the entire system was pressurized using nitrogen gas to suppress liquid flow instabilities due to the generation of cavitation at the saturated system pressure. To enhance boiling heat transfer, the surface was electrically deposited with fine diamond particles (mixture of particles with diameters 20 and 1.5 m), and an electric field of −5 kV/mm was applied between the surface and slit electrode. The experiments were conducted under various system pressures (75–230 kPa), mass flow rates (1.67–5.00 g/s), and degrees of subcooling (5–15 K) to evaluate the heat transfer performance. The electric field was effective in increasing both the critical heat flux (CHF) and heat transfer coefficient (HTC). The high electric field enhanced the boiling heat transfer until the inflow liquid entirely evaporated. Increasing the mass flow rate was also effective in increasing the CHF and HTC at lower wall temperatures, resulting in a maximum of 101 W/cm 2 at 64 °C and 37 kW/m 2 ·K at 52 °C, respectively. Increasing the system pressure improved the HTC but elevated the wall temperature. Subcooling was effective in increasing HTC. Increase in either pressure or subcooling did not change the CHF because the entire inflow liquid evaporated in the MSC chamber due to the electric field","PeriodicalId":17405,"journal":{"name":"Journal of Thermal Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.2000,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Thermal Science and Technology","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1299/jtst.2021jtst0033","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"THERMODYNAMICS","Score":null,"Total":0}
引用次数: 2
Abstract
the capacity of MC for heat flux values from 2.17 to 33.53 W/cm 2 at a system pressure of 100 kPa, an inlet degree of Abstract In this study, the cooling capabilities of flow boiling heat transfer aided by electrohydrodynamic (EHD) force and diamond-electrodeposited boiling surface is investigated in a micro-slit channel (MSC). The MSC uses a two-phase flow cooling system, in which an electric field is applied to a dielectric liquid using a slit electrode. To reduce the wall temperature below 60 °C and promote cooling in electronic devices, a dielectric liquid with a saturation temperature of 15 °C HCFO-1224yd (AGC, AMOLEA, CF 3 CF = CHCI) was selected as a working fluid. Moreover, the entire system was pressurized using nitrogen gas to suppress liquid flow instabilities due to the generation of cavitation at the saturated system pressure. To enhance boiling heat transfer, the surface was electrically deposited with fine diamond particles (mixture of particles with diameters 20 and 1.5 m), and an electric field of −5 kV/mm was applied between the surface and slit electrode. The experiments were conducted under various system pressures (75–230 kPa), mass flow rates (1.67–5.00 g/s), and degrees of subcooling (5–15 K) to evaluate the heat transfer performance. The electric field was effective in increasing both the critical heat flux (CHF) and heat transfer coefficient (HTC). The high electric field enhanced the boiling heat transfer until the inflow liquid entirely evaporated. Increasing the mass flow rate was also effective in increasing the CHF and HTC at lower wall temperatures, resulting in a maximum of 101 W/cm 2 at 64 °C and 37 kW/m 2 ·K at 52 °C, respectively. Increasing the system pressure improved the HTC but elevated the wall temperature. Subcooling was effective in increasing HTC. Increase in either pressure or subcooling did not change the CHF because the entire inflow liquid evaporated in the MSC chamber due to the electric field
期刊介绍:
JTST covers a variety of fields in thermal engineering including heat and mass transfer, thermodynamics, combustion, bio-heat transfer, micro- and macro-scale transport phenomena and practical thermal problems in industrial applications.