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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

A GENERAL THERMAL RESISTANCE WITH CORRECTION FACTOR FOR HEAT EXCHANGER DESIGN AND ANALYSIS BASED ON POWER FLOW METHOD

Get access (open in a dialog) DOI: 10.1615/IHTC16.her.023388
pages 4583-4590

Аннотация

Thermal resistances of heat exchangers are the basic for the applications of power flow method in the heat transfer characteristic analysis and performance optimization of heat transfer systems. However, deducing the thermal resistance expressions of some complex flow arrangement heat exchangers are not easy and become the obstacle for the application. The study concluded the "Ohm's law" for heat exchanger analysis by combining the entransy dissipation-based thermal resistance (EDTR) defined by the characteristic temperature difference including arithmetic mean temperature difference (AMTD) and inlet temperature difference (ITD). Based on the EDTR, we introduced the log mean temperature difference (LMTD) correction factor and proposed the hot-end and cold-end NTUs for developing a universal expression of thermal resistance for a variety of heat exchangers on the basis of the ITD-driven thermal resistance form of the counter-flow heat exchanger. The correction factor represents the correct and effective thermal conductance for a complex flow arrangement heat exchanger compared with the counter-flow heat exchanger, and it is influenced by the geometry of the heat exchanger and the heat capacity rates of the hot and cold fluids. Moreover, the research revealed the temperature effectiveness of a heat exchanger is the ratio of the heat transport resistance of cold fluid to the corresponding thermal resistance. Finally, a case showed that the unified expression of thermal resistance is feasible for describing the heat transfer performance of heat exchangers from the power flow perspective.