Thermoelectric plant with gas/steam cycle for the complete conversion of heat into mechanical work

摘要

A thermoelectric plant with a so-called "gas/steam cycle" is proposed which is operated between the overheated and saturated to dry saturated state of a superheated or cold steam and consequently avoids the constant heating and evaporation of the feed liquid by means of the boiler or evaporator. The return of the wet steam (X APPROX 0.9) can therefore be carried out with normal turbocompressors or piston-type machines (Figs. 1 and 1.1). The cycle passes through the following states (Figs. 2-3, shown for simple overheating): 1)Isobaric heat absorption from the dew point to far into the overheating region (gaseous state): state 1 -> 2, 2)adiabatic/isentropic expansion into the saturation state (X APPROX 0.9) with kappa = 1.3, with work being performed: state 2 -> 3, 3)adiabatic/isentropic compression of the wet steam with kappa = 1.135 with work being expended and, consequently, completion of the cycle: state 3 -> 1. The area enclosed between the three states in the pressure/volume diagram (Fig. 2) is equal to the differential work Weff from the two work processes; it is equivalent to the heat qu absorbed on the primary side. The thermal efficiency of the plant (expansion plus compression machine) is consequently 100% and therefore independent of the thermodynamic temperature drop present in each case. The useful heat area can be increased by high temperatures and repeated intermediate overheating and the useful work ratio (work of expansion/work of compression) of the plant can consequently be increased (Figs. 4 and 5).