Is 600J the Minimum Heat Transfer to Maintain Entropy in a Thermodynamic Cycle?

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SUMMARY

The discussion centers on the minimum heat transfer required to maintain entropy in a thermodynamic cycle. The working substance absorbs heat Q1 = 1000J from a reservoir at T1 = 1000K and Q2 = 2000J from a reservoir at T2 = 2000K. To comply with the second law of thermodynamics, the minimum heat transfer to the reservoir at T3 = 300K must be 600J. This conclusion is based on the requirement that the total entropy change of the system must be greater than or equal to zero.

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Bigfoots mum
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Hi, i just want to check my reasoning on this problem.

A working substance is taken around a closed cycle that involves performing some external work. It absorbes heat Q1 = 1000J from a resevoir at T1 = 1000K, and heat Q2 = 2000J from a resevoir at T2 =2000K. The only other exchange of heat is with a resevoir at T3 = 300K.
What is the minimum heat that must have been transferred from the substance to the resevoir at T3 ( explain your reasoning)?

Now i think the minimum heat is 600J, as the entropy change of the system must be >= 0, and we must have heat rejection otherwise we'd violate the 2nd law. Is this ok?
Thanks
 
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Hi Bigfoots mum, welcome to PF. Your reasoning looks good to me.
 

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