smaller package volume than usual. It can be used in conjunction with the main radiator to provide more cooling for another mission demanding higher cooling rates. It can fill the niche of a backup system when the main radiator fails. Of course, the radiator can be used by itself in cases where tight contraints do not allow using a standard radiator. In the following pages, this radiator system is presented together with its coolant loop. We also compare experimental results with those obtained from numerical simulations. The concept of our proposed deployable film radiator is shown in Fig. 1. The radiator is of a liquid fluid type. Radiator fin thickness is less than 0.6 mm, with the radiator material being aluminum. The radiator itself is constructed via the rollbonding method, with the part becoming the coolant flow path left unbonded by use of an isolator. Due to this method of construction we can chose the coolant flow path as we please. The simplicity of the two plate structure and the form means that thermal resistance is less than that of ordinary radiators. When no coolant is in the flow paths, they remain deflated. The radiator is therefore akin to a thin plate which can then be tightly rolled up. Even if the radiator is long, it is the radiator fin thickness which contributes most to the roll volume. The radiator is rolled out by the pressure of the coolant through the tubes, which inflate. The coolant pressure required is about 0.1 or 0.2 MPa. Figure 2 shows a schematic of the complete cooling system, which is composed of our proposed radiator, a coolant circulating pump and a coolant tank. Coolant flowrate is controlled by the pump rotation. The coolant tank also contains pressurized gas, separated from it by a piston. Two valves regulate the system: one is set between the pump and the radiator, the other between the coolant tank and the radiator. When inactive, coolant remains in the tank and the radiator is rolled up. (Since no coolant resides in the radiator at this point there is no possibility of it freezing in the tubes.) At activation, both valves are opened. The pressurized gas in the tank drives the piston, which thereupon pushes the coolant into the radiator and thus unrolls it. Since the static pressure of the coolant is controlled by the pressure of the gas, adding
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