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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

CONDENSATION HEAT TRANSFER ENHANCEMENT OF R245FA IN TUBE WITH CONICAL MESH INSERTS

Get access (open in a dialog) DOI: 10.1615/IHTC16.cod.022566
pages 2165-2179

Аннотация

Organic fluids are generally used for low grade energy utilization due to low saturation temperature. However, condensation heat transfer coefficients of organic fluids are even lower than forced convective heat transfer coefficients of water, yielding large size and high investment cost of heat exchangers. Here, conical mesh inserts with micro-pores are newly designed to enhance condensation heat transfer of R245fa in horizontal tube. Conical mesh insert works better than mesh cylinder insert utilized in our previous work for condensation heat transfer enhancement. The maximum heat transfer enhancement factors can be up to 1.98. Three mechanisms for heat transfer enhancement are involved: (1) Liquid droplets entrained in vapor core are captured by the conical mesh insert surface, decreasing deposition possibility of droplets to have thin liquid film on the tube wall. (2) Liquid from conical mesh insert outlet activates the vapor-liquid interfacial wave. (3) Vapor velocities are increased and synergetic with temperature gradient near the tube wall. We demonstrate a new way to enhance macro properties of condensation heat transfer using mesh screen with micro structures.