Thermal performance verification for the JEM MAXI Loop Heat Pipe Radiator System
- Paper number
IAC-05-B4.3.08
- Author
Dr. Hiroki Nagai, Tohoku University, Japan
- Coauthor
Dr. Shiro Ueno, Japan Aerospace Exploration Agency (JAXA), Japan
- Year
2005
- Abstract
The thermal performance of the Loop Heat Pipe Radiator System (LHPRS) has been verified in the thermal vacuum testing. The Monitor of All-sky X-ray Image (MAXI) is an X-ray all-sky monitor, which has been selected as a payload on JEM Exposed Facility. MAXI will scan the whole sky as the ISS orbits around the earth. MAXI is equipped with two kinds of X-ray slit cameras, a Gas Slit Camera (GSC) and a Solid-state Slit Camera (SSC). The detection sensitivity of them is the highest among those ever developed as all-sky monitors. MAXI is to perform the systematic survey of the X-ray variability to study the nature of the active celestial objects. The SSC consists of 32 X-ray CCD chips. Each chip is cooled down to -60 deg C by a Peltier device and the heat from the hot side of the Peltier device (camera body) is rejected from the two radiators. These radiators are placed on the top and front sides of the MAXI package. The Loop Heat Pipe, which is a passive two-phase thermal control system, is used to transport tens of watts of heat from the Peltier devices to the radiators. MAXI is the first Japanese space mission to use a LHP. The MAXI LHP differs from conventional LHPs in the configuration that it has two condensers connected in parallel to a common evaporator. Each of the condensers has a different radiation area and hence has a different length. Moreover, their thermal conditions are different because they point toward different directions (yaw axis and roll axis) and the sink temperatures changes periodically due to the ISS orbital thermal environment. Since it is possible that the heat transportation deviates to one condenser only, we should investigate how the double condensers affect the LHP performance under various conditions. We have conducted thermal vacuum testing for the engineering model of the MAXI LHPRS. It consists of (1) Steady state operation, (2) Startup tests, and (3) Condenser imbalance. In this paper, we describe the test result and performance verification of the MAXI LHPRS. We focus on the transient and start-up behavior due to the effect of double-condenser, and the transient thermal behavior in the case where there was a large temperature differential between the two radiators.
- Abstract document
- Manuscript document
IAC-05-B4.3.08.pdf (🔒 authorized access only).
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