Approach of design of electric heaters used in non hermetically sealed structure spacecrafts

A design feature of the construction of electric heaters for non-pressurized spacecraft using a heating element in the form of a tape of a material with high resistivity, located on a flat base (electrical insulating substrate) in the form of a snake with the organization of the necessary gaps between the tapes, is revealed. A mathematical model has been developed for calculating the main design parameters of electric heaters: power, mass, heated surface area. The nomenclature of efficiency indicators used as optimization criteria has been formed: power utilization factor, filling factor of an electrically insulating substrate tape, surface density, energy-mass efficiency, thermal efficiency of heating, target efficiency. The methodological principles for ranking the requirements for the parameters of electric heaters are determined using the selected optimization criteria: the preferred use of tape materials with high resistivity and minimum thickness. A method is formulated for step-by-step calculation of the parameters of electric heaters in the presence of restrictions on the maximum heat flux density determined from the conditions for the use of electric heaters. General recommendations have been developed for choosing the parameters of electric heaters: use increased voltage, minimize the thickness of the heating element tape and the width of the gap between the tapes, determine the minimum value of the tape length for the maximum heat flux density at a given voltage rating.