In response to the identified needs of emerging high power spacecraft applications, a multiple evaporator hybrid loop heat pipe (H-LHP) was developed and tested as part of a Dual Use Science and Technology (DUS&T) program co-sponsored by ATK and AFRL/PRP. During the course of the DUS&T program, a two-kilowatt system with three evaporators was developed and tested to identify viable system architectures and characterize system performance capabilities as a function of heat load profiles and spatial distribution of the evaporators. Following the successful development of the two-kilowatt system, a 10-kilowatt system with six evaporators was fabricated and tested. Tests were performed with the system operating in a totally passive mode, where applying a small amount of power to a sweepage evaporator provides the auxiliary flow through the primary evaporators, and as a self-regulating, capillary-controlled mechanically pumped system. This paper will provide a description of the 10-kilowatt multievaporator system and present the results of the passive and mechanically pump test programs.The effort described in this paper includes selection of the appropriate thermal architecture through a brief literature review of state-of-the-art technology; refinement of the architecture details via testing of a three-evaporator development test bed and exercising a Thermal Desktop Sinda/Fluint thermal model; and program culmination with the fabrication and demonstration of a two-phase liquid-pumped high-power Ground Demonstration System with capillary-controlled flow regulation (no control valves) having a 10-kW coohng capacity that is readily capable of scaling to larger systems. TECHNICAL BACKGROUNDThis section begins with an overview of common requirements for potential applications in high power spacecraft. Once potential application requirements were identified, a comprehensive literature search was performed in order CP969, Space Technology and Applications International Forum-STAIF 2008, edited by M. S. El-Genk
The capillary pumped loop (CPL) is a state-of-the-art technology for cooling spacecraft and telecommunication devices. It is a two-phase heat-transport device in which the driving force is provided by the capillary action of the wick material in the evaporator. Compared to the widely used heat pipes, it provides a higher heat-transport capacity, more exibility of installation, and greater heat-transport distance because of wickless transport lines and the absence of liquid and vapor counter owing. The major disadvantagesof the CPL are long and complicated startup procedures and the possibility of deprime at high heat input and large load variations. This paper investigates the liquid-vapor separation and thermal management with the electrohydrodynamic (EHD) technique for an EHD-assisted CPL using R-134a as the working uid. An experimental investigation, along with a mechanism analysis, was employed to evaluate the potential of the EHD technique for thermal performance improvement of CPL systems. Experimental results showed that enhancements, up to three times, could be obtained in heat-transfer coef cients by applying an electric eld at different heat load levels. The depriming conditions of a capillary pump can also be prevented with the EHD technique. NomenclatureA = surface area a = object radius E = electric eld strength F = electrohydrodynamic(EHD) force h = heat-transfer coef cient I = heater's current i = discharge current L = length N = number of thermocouples Q = heat-transfer rate or power T = temperature V = heater's voltage D P = pressure drop ² = permittivity g = enhancement factor j = dielectric constant q = density u = EHD potential Subscripts c = capillary e = electric g = gravity h = heater l = liquid or loop ref = reference t = total v = vapor w = wick or wall
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.