MECOP - A Novel Two Phase Capillary Technology for the Thermal Control of Space Systems

In the thermal control of space systems, two-phase fluid circuits based on capillary pumps, particularly Loop Heat Pipes (LHPs), are efficient and well-established devices. However, traditional LHPs have limitations that can hinder or even prevent their application in several applications: a. Heat is extracted in a localized manner through the small saddle of the evaporator, necessitating additional support from doublers or heat pipe banks, or requiring an increased number of LHPs; b. LHPs are typically delivered as pre-assembled, pre-charged, and sealed circuits, which can complicate integration into a spacecraft, particularly in cases involving to cross the pressurized shell of a space habitat; c. LHPs generally require a high degree of customization, leading to significant impacts on schedule and cost. The challenge that motivated the study outlined in this article was to develop a new two-phase capillary technology to overcome these limitations: being as compact, modular, and scalable as possible, enabling easy assembly and filling during the spacecraft system integration phase, including an evaporator capable of efficiently collecting heat from large or distributed areas, similar to a standard cold plate. The novel modular-LHP technologies proposed by Allatherm in recent years provided a foundation for pursuing these objectives through a comprehensive approach. A key element of the innovation is MECOP (Multievaporator Cold Plate), a multi-module evaporator designed for heat collection from extensive or multiple areas. This paper describes the development, technical details and verification of a modular LHP class featuring the MECOP evaporator. It also discusses its application in the thermal management of manned space infrastructures, demonstrating that the modular-LHP approach enables the effective and practical use of capillary heat loops to extract waste heat from a pressurized cabin. A review of the working fluids with long-term operation life with MECOP is given.