作者asdghjk789 (葡萄果酱)
看板ChemEng
标题[问题] 化工热力学(500p)
时间Tue Nov 22 22:30:12 2011
Three processes are described below for a single phase fluid whose internal
energy depends only on temperature.Is any of the processes imposible? Use
the thermodynamics principles(first law and relationship of internal energy
to temperature)to explain why it is impossible.
(1)
A fluid contracts as it is pushed by a piston in an adiabatic prosess and
its temperature remains constant.
(2)
A fluid contracts as it is pushed by a piston and cooled,and its temperature
goes up.("cooled"means heat transfer out)
(3)
A fluid expands pushing a piston as it is heated and its temperature goes down
请求解题!!
急需(_ _)
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◆ From: 219.84.210.8
※ 编辑: asdghjk789 来自: 219.84.210.8 (11/22 22:32)
1F：推 thermalBolo:delta u = q-w (1)q=0, w<0, u>0 111.248.1.107 11/23 00:49
2F：→ thermalBolo:(2)q<0, w<0, du不一定大於或小於0 111.248.1.107 11/23 00:51
3F：→ thermalBolo:(3)q>0, w>0, du不一定大於或小於0 111.248.1.107 11/23 00:52
4F：→ thermalBolo:因为u=f(T) only, du=C*dT, 111.248.1.107 11/23 00:54
5F：→ thermalBolo:C=Cv(for理想气体)或Cs(for固液) 111.248.1.107 11/23 00:55
6F：→ thermalBolo:所以(2)和(3)有可能；(1)不可能。 111.248.1.107 11/23 00:55
7F：推 thermalBolo:thx ^^ 111.248.1.107 11/24 03:24