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.