英语翻译A further problem associated with steam is that ithas ve
英语翻译 A further problem associated with steam is that it has very low vapour pressures at normal condensing conditions required in vapour power plant rejecting heat either to a cooling water stream or to the atmosphere. Thus,at a condensing temperature of 40 ◦C,the vapour pressure of steam is only 0.074 bar.This means that the density of the expanded steam is very low and huge and expensive turbines are required,while there are problems with maintaining a vacuum in the condenser.In contrast to this,pentane at 40 ◦C has a vapour pressure of 1.15 bar.It is therefore far more dense and,consequently,the expander required for it will be much smaller and cheaper.