In order to reduce the radiative exchange between two large, parallel plates, a thin, flat radiation protection shield is introduced between the plates. However, the emissivities of the two surfaces...

In order to reduce the radiative exchange between two large, parallel plates, a thin, flat radiation protection shield is introduced between the plates. However, the emissivities of the two surfaces of the shield are different; one surface has emissivity εS <>

a) The protection shield is to be orientated so that the heat flow transferred is as small as possible. Should the side with the emissivity εS be directed to the plate at the temperature T1 > T2, or is the opposite arrangement better?

b) Which of the two orientations leads to the higher temperature TS of the protection shield?