Notes

• NOTE 1 The radiative sink temperature includes both the natural environment load (solar, planetary albedo and infrared fluxes) and the radiative exchanges with other items.
• NOTE 2 The radiative sink temperature is typically used to provide a simplified interface for an item, to provide a means for parameter studies thus avoiding extensive calculations or to define adequate radiative boundary conditions for thermal tests.
• NOTE 3 The sink temperature TSink of an item i with a temperature Ti in radiative exchange with n items j and submitted to external radiative environmental fluxes is calculated according to the formula: where emissivity of item i Ps absorbed solar flux on item i PA absorbed (planetary) albedo flux on item i PIR absorbed infrared (planetary) flux on item i Rij radiative coupling between item i and item j Tj temperature of item j s Stefan-Boltzmann constant Ai radiative exchange area of item i
• NOTE 4 The radiative sink temperature formula is defined for steady state and transient conditions. Depending on the degree of interaction between the item (via its temperature, surface properties, dimensions, heat dissipation) and the radiative sink, the simplified approach using the radiative sink temperature is performed in an iterative way during the course of a project.