Optimization of wick shape in a loop heat pipe for high heat transfer. (January 2017)

• Record Type: Journal Article
• Authors: Nishikawara, M.; Nagano, H.
• Is Part Of: International journal of heat and mass transfer. Volume 104(2017:Jan.)
• Page Start: 1083
• Page End: 1089
• Publication Date: 2017-01
• Subjects: Capillary evaporator -- Capillary pumped loops -- Evaporator heat-transfer coefficient -- Loop heat pipe -- Optimized wick shape -- Three-phase contact line; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.09.027
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Optimum wick shape was achieved by just using a three-phase contact line. Evaporator heat-transfer coefficient was formulated considering groove pressure loss. Heat-transfer coefficient reached a local maximum using the contact-line length. Contact-line lengths and heat-transport contributions in literature are evaluated. Abstract: This paper presents a method to optimize wick shape in the capillary evaporator of loop heat pipes and capillary pumped loops. The evaporator heat-transfer coefficient is maximized using only the length of a three-phase contact line (TPCL) within the case, wick, and grooves as a variable wick dimension. The heat-transfer coefficient is formulated taking the following two particular aspects into account. The heat-transfer coefficient initially increases with TPCL length. However, when TPCL becomes too long, the heat-transfer coefficient decreases because of a large pressure loss in the grooves. The proposed model is validated experimentally. Both the model and experiment show the heat-transfer coefficient reached a local maximum in terms of the TPCL length. It is concluded that wick shape can be optimized by just using the TPCL length. The effects of the material of an evaporator's case, wick, and working fluid are also discussed.