In an engine, ( ) energy is converted into mechanical energy. In a compressed steam refrigeration cycle, the working mediun ) (filling: absorbs or releases) heat in the evaporator. Steam power plants generally include four parts: ( ) and feedwater pumps. ),( 1 MPa =( ) bar. If the entropy S is 10 J/K, S is 20 J/K, the temperature T is 300 K, the absorption heat Q is ( )J. (6) A shell and tube heat exchanger mainly consists of shells and ( ) (7) If the thermal conductivity and thickness of a large flat wall are 0. W/(m K) and 0.25 m, then the thermal resistance per unit area is ( m K/W. (8) In a heat exchanger with downstream flow, -80 C, -50 C =10 C, =30 C, the logarithmic mean temperature difference ( ) C.