【摘要】 在自然界发生的实际过程,总伴随能量在质方面的耗散,本来可以做功的那部份能量丧失其做功能力而转变成热（q_n、u）,成为不可用能（W_L）,它的多少与过程的总熵变△S 总（系统的熵变和环境熵变之和）存在关系dS_总=δ_q(n、（?）/T=δW_L/T式中 T 为系统温度、当系统与环境（温度为T₀）有热交换时,T=T₀。把熵与不可用能结合起来,它的意义直观清楚,有利教学。更多还原

【Abstract】 Processes that actually occur in nature are accompanied by dissipating in the character of energy.Energy which originally can do work loses the ability of doing work and transforms into heat （q_n,u）,turning into unavailable energy（WL）.Its amount relates to the toal entropy change in process △S_total（tho system entropy change plus the entropy change of its surroundings）.There is dS_total=δW_L/T=δq_{n. u}/T T becomes To in the formula when the temperature of finalstate of a system is equal to the temperature of its surroundings,combining the entropy with unavailable energy.Its meaning is intuitional and clear, and so is convenient for teaching and studying.更多还原