00:01
Hello student, first law of thermodynamics will hold in this case when q dot h1 falls to q dot l1 plus w1 dot and q dot h2 falls to q dot l2 plus w2.
00:36
Now for three case a, b and c, these two conditions are satisfied.
00:42
So for all the three case, for cases a, b and c, first law of thermodynamics is satisfied.
01:12
Now we have to check the second law of thermodynamics.
01:24
So to check the second law of thermodynamics, we have to consider, we have to combine the heat engine and the heat pump together and consider as a single.
01:41
Now the heat taken from the reservoir, hot reservoir, here this is the hot reservoir, this is the cold sink.
01:52
So heat taken from the hot reservoir, q1 equals to q dot h1 minus q dot h2 and heat rejected in the sink, heat rejected in the sink, q2 equals to ql1 minus ql2 dot.
02:54
Now work done, work done by the combined engine, w equals to w1 dot minus w2 dot.
03:20
Now the second law will violate, will violate when, when q1 equals to, violate when q1 equals to w and q2 is zero, that is the heat taken from the hot reservoir is completely converted to work without rejecting any heat to the sink.
04:08
So this is not possible.
04:09
In this case efficiency will be 100 percent, which is not possible...