Experimental investigation on two-phase thermosyphon loop with partially liquid-filled downcomer

Two-phase thermosyphon loops (TPTLs) are beginning to be extensively used in the field of air conditioning and heat recovery, where they have quite different flow characteristics compared with the traditional TPTLs used in cooling of electronics. However, in the existing studies, the flow features in the downcomer were ignored, and most researchers simply thought the downcomer was always full of liquid. In this study, a visual experimental setup was established, the flow features in the downcomer were observed and measured. And the influencing factors including temperature difference, liquid charge, height difference, and circulation flow resistance on the liquid head have been identified and investigated experimentally. The results show that, different from the conventional understandings, the downcomer can be partially liquid filled. At this time, the upper part of downcomer is a static saturation gas blockage, surrounded by a layer of liquid film, which does not provide the driving force. The liquid head in the downcomer, which provides the driving force, shows great self-regulation ability with different working conditions. Increasing the refrigerant charge, temperature difference, circulation flow resistance, and decreasing the height difference drives the liquid head to rise, and the downcomer tends to be fully liquid filled.

[1]  Zhang Hainan,et al.  Integrated system of mechanical refrigeration and thermosyphon for free cooling of data centers , 2015 .

[2]  Khosrow Jafarpur,et al.  Year-round outdoor experiments on a multi-stage active solar still with different numbers of solar collectors , 2015 .

[3]  Stéphane Le Masson,et al.  Two-phase thermosyphon loop for cooling outdoor telecommunication equipments , 2013 .

[4]  Y. Joshi,et al.  A Natural Circulation Model of the Closed Loop, Two-Phase Thermosyphon for Electronics Cooling , 2001, Heat Transfer: Volume 7 — Heat Transfer in Electronic Equipment, Student Research, and Visualization Techniques.

[5]  Baolong Wang,et al.  Development of an integrated air conditioner with thermosyphon and the application in mobile phone base station , 2013 .

[6]  Alessandro Franco,et al.  Closed Loop Two-Phase Thermosyphon of Small Dimensions: a Review of the Experimental Results , 2012 .

[7]  Rahmatollah Khodabandeh.  Pressure drop in riser and evaporator in an advanced two-phase thermosyphon loop , 2005 .

[8]  Hoon Kang,et al.  Performance optimization of a hybrid cooler combining vapor compression and natural circulation cycles , 2009 .

[9]  I. M. Michaelides,et al.  Computer simulation of the performance of a thermosyphon solar water-heater , 1992 .

[10]  Pallippattu Krishnan Vijayan,et al.  A generalized flow correlation for two-phase natural circulation loops , 2006 .

[11]  Jackson Braz Marcinichen,et al.  A review of on-chip micro-evaporation: Experimental evaluation of liquid pumping and vapor compression driven cooling systems and control , 2012 .

[12]  Paul Byrne,et al.  Experimental study of an air-source heat pump for simultaneous heating and cooling – Part 2: Dynamic behaviour and two-phase thermosiphon defrosting technique , 2011 .

[13]  James E. Braun,et al.  System modeling and operation characteristics of thermosyphon solar water heaters , 1985 .

[14]  N. M. Rao,et al.  Steady-state performance of a two-phase natural circulation loop , 2006 .

[15]  Xiaohua Liu,et al.  Energy performance analysis on telecommunication base station , 2011 .

[16]  Paul Byrne,et al.  Experimental study of an air-source heat pump for simultaneous heating and cooling - Part 1: Basic concepts and performance verification , 2011 .

[17]  Aliakbar Akbarzadeh,et al.  Waste Heat Recovery Using Loop Thermosyphons Heat Exchanger (LTHE) In Buttercup Bakery , 2000 .

[18]  Xianting Li,et al.  Heat recovery from Internet data centers for space heating based on an integrated air conditioner with thermosyphon , 2015 .

[19]  Bin-Juine Huang,et al.  A performance test method of solar thermosyphon systems , 1991 .

[20]  Brian Norton,et al.  Aqueous propylene-glycol concentrations for the freeze protection of thermosyphon solar energy water heaters , 1991 .

[21]  Zhen Li,et al.  Modelling and applications of annual energy-using simulation module of separated heat pipe heat exchanger , 2013 .

[22]  Georgios Martinopoulos,et al.  Identification of the environmental impact from the use of different materials in domestic solar hot water systems , 2013 .

[23]  R. Mei,et al.  A Flow Boiling Microchannel Evaporator Plate for Fuel Cell Thermal Management , 2007 .

[24]  Fu-Yun Zhao,et al.  Modeling and experimental investigation of looped separate heat pipe as waste heat recovery facility , 2006 .

[25]  Kazuhiro Takeshita,et al.  The Effect of Subcooling on the Flow and Heat Transfer Characteristics in a Two-Phase Loop Thermosyphon , 2011 .

[26]  Rahmatollah Khodabandeh.  Heat transfer in the evaporator of an advanced two-phase thermosyphon loop , 2005 .

[27]  Jackson Braz Marcinichen,et al.  Dynamic flow control and performance comparison of different concepts of two-phase on-chip cooling cycles , 2014 .

[28]  Rahmatollah Khodabandeh,et al.  Instability, heat transfer and flow regime in a two-phase flow thermosyphon loop at different diameter evaporator channel , 2010 .

[29]  P. Vijayan,et al.  Study on the stability behaviour of two-phase natural circulation systems using a four-equation drift flux model , 2007 .