1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Machine 2nd degree or

  1. Apr 3, 2017 #1


    User Avatar

    Concerning Global warming; Can we cool atmosphere by converting it's heat content to electricity? if we do so is it became a perpetual machine in 2nd degree or not?
    I'm not so good in thermodynamics. But I'm sure it will not violate 1. rule energy is not created from noting, energy converted from one form to another. But not sure with 2. rule. Honestly, I did not understood well this axiom. "heat always flows spontaneously from hotter to colder bodies, and never the reverse, unless external work is performed on the system" OK no objection. Heat pumps uses energy to pump heat from colder bodies to hotter bodies. no confliction.but "total entropy of an isolated system can only increase over time. It can remain constant in ideal cases where the system is in a steady state (equilibrium) or undergoing a reversible process." is not clear since if heat will flow from hotter region to cooler region this axiom is ok for cooler region but entropy will reduced in hotter region. it is confusing me.
    No arrangement can go beyond Carnot's upper limit to the efficiency of conversion of heat to work in a heat engine. Is it applicable for heat pumps? (As my knowledge, heat pumps is working in reverse Carnot cycle).
    Heat engines may be bound by efficiency, but again with my knowledge Heat pumps defined by C.O.P. values that defines how much energy transferred from colder region to hotter region with a unit of energy. (typically 1:3)
    If we transfer 3 unit of energy with 1 unit energy and operate heat pump in hotter region. The net energy insert in hotter region is 4 times of energy needed to heat pump.
    Heat flow (energy) is a through variable. Total of through variables entering a node must be zero indicating at least one of the through variable must exit from node. Then we can drive out 4 unit of energy from hotter region.
    If we feed back 1 unit energy to operate heat pump and loose 1 unit in conversion time we can draw 2 unit energy.
    if we look the picture again, we will see an apparatus consuming no fuel or visible energy producing energy
    those type machines named as perpetual machine (at least 2nd degree)
    But I could not pointing violated rules.
    Can any one point which rule is violated?
    or this system is not perpetual?
    Last edited: Apr 3, 2017
  2. jcsd
  3. Apr 3, 2017 #2


    User Avatar

    Staff: Mentor

    What would happen to the electricity? In other words, how would that conversion ultimately lead to a reduction of overall energy? Proposals for AGW mitigation require that heat be dumped back into space (reflecting sunlight, removing CO2 such that less heat is retained by the atmosphere, etc.)

    As for why you can't use a refrigerator for fooling in a closed system, to best is to consider a Carnot engine and a Carnot refrigerator coupled together: the output of the engine is what drives the refrigerator, with both systems working with the same hot and cold reservoirs. Doing the calculation, you will see that the overall system is leading to energy being transferred from the hot to the cold reservoirs, same as if they were simply connected by thermal conduction.
  4. Apr 3, 2017 #3


    User Avatar

    After converting to electricity life will be more easy. You can convert to electromagnetic wave (radio wave or light) and transmit to space. If consumed on earth for work (wiser) than people may not need to convert any other fuel (fossil or nuclear) to heat. the total Heat will stay in same level. the present cooling process (which is dumping energy into space) eventually lead reduction of overall energy
    Why do you assume Carnot engine Driving Carnot refrigerator and working with same reservoirs?
    Carnot refrigerators' COP value is at least 1:3 that with 1 unit energy you can transfer 3 unit energy from colder place to hotter place.
    than you can convert and transmit to different reservoirs (to third universe)
  5. Apr 3, 2017 #4


    User Avatar

    Also your Carnot engine and reverse engine setup may also say large amount of heat may be transferred with small amount of work.:wink:
    Additionally you can utilize electric in either chemical or physical energy storage eg
    Redox reactions or pumping water from sea level to higher altitudes
    there is infinite way to consume electric without converting to heat
    Last edited: Apr 3, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Machine 2nd degree or
  1. Engineering a machine (Replies: 1)

  2. Perpetual Machines (Replies: 17)

  3. Vending Machine ? (Replies: 4)

  4. Microwave Machine ~ (Replies: 1)

  5. Machining rifling (Replies: 1)