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The flow boiling heat transfer coefficients of R-134a/R-290/R-600a (91%:4.068%:4.932% by mass) refrigerant mixture are experimentally
arrived in two tubes of diameter 9.52 and 12.7 mm. The tests are conducted to target the varied heat flux condition and stratified
flow pattern found in evaporators of refrigerators and deep freezers. The varied heat flux condition is imposed on the refrigerant
using a coaxial counter-current heat exchanger test section. The experiments are performed for mass flow rates of the refrigerant
mixture between 3 and 5 g s−1 and entry temperature between −8.59 and 5.33°C which are bubble temperatures corresponding to a pressure of 3.2 and 5 bar.
The influences of heat flux, mass flow rate, pressure, flow pattern, tube diameter on the heat transfer coefficient are discussed.
The profound effects of nucleate boiling prevailing even at higher vapor qualities in evaporators are highlighted. The heat
transfer coefficient of the refrigerant mixture is also compared with that of R-134a. 相似文献
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Prabakaran Rajendran Prasanna Naveen Kumar J. Mohan Lal Dhasan Selvam C. Harish Sivasankaran 《Journal of Thermal Analysis and Calorimetry》2020,139(2):941-952
Journal of Thermal Analysis and Calorimetry - In the present work, the melting behavior of a fatty acid-based phase change material (PCM) with the addition of functionalized graphene nanoplatelets... 相似文献
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Prabakaran Rajendran Lal Dhasan Mohan Devotta Sukumar 《Journal of Thermal Analysis and Calorimetry》2021,143(1):335-350
Journal of Thermal Analysis and Calorimetry - In this work, the performance enhancement of a HFO-1234yf mobile air conditioning (MAC) system with a suction/liquid line heat exchanger (SLHX) was... 相似文献
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A simple, safe, rapid and economical method was developed for the isolation of high-purity forskolin from Coleus forskohlii roots using activated charcoal as an adsorbent in a column. The elution was carried out under reduced pressure to make the process rapid. Activated charcoal acted as a reversed phase adsorbent and allowed elution of forskolin without much impurities. The residue, obtained from the eluate was purified and crystallized using different solvent mixtures to obtain pure forskolin. The forskolin isolated was analyzed and characterized by UV, IR, RP-HPLC, electrospray ionization MS, 1H NMR and 13C NMR. The yield was 0.097% w/w (RSD 5.6%). The purity was 96.9% w/w (RSD 0.3%) as determined by RP-HPLC. The present method enables researchers to produce high-purity forskolin in their labs by using common chemicals. 相似文献
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Lazarus Godson Asirvatham Balakrishnan Raja Dhasan Mohan Lal Somchai Wongwises 《Particuology》2011,9(6):626-631
To investigate the convective heat transfer of nanofluids, experiments were performed using silver–water nanofluids under laminar, transition and turbulent flow regimes in a horizontal 4.3 mm inner-diameter tube-in-tube counter-current heat transfer test section. The volume concentration of the nanoparticles varied from 0.3% to 0.9% in steps of 0.3%, and the effects of thermo-physical properties, inlet temperature, volume concentration, and mass flow rate on heat transfer coefficient were investigated. Experiments showed that the suspended nanoparticles remarkably increased the convective heat transfer coefficient, by as much as 28.7% and 69.3% for 0.3% and 0.9% of silver content, respectively. Based on the experimental results a correlation was developed to predict the Nusselt number of the silver–water nanofluid, with ±10% agreement between experiments and prediction. 相似文献
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