I have only seen absorption heat pumps that use entropy to pump heat, but is there such heat pump that uses just continuously replenished thermal energy alone to pump heat from one location to another. This would have the enormous advantages of being able to generating power without a cold sink, allowing heat engines to operate outside of our atmosphere, say on a lunar base. It also add stealth to nuclear submarines because they would not leave a quot;thermal wakequot;.
It wouldn't be a heat pump if it only had one heat exchange region, it wouldn't be a heat pump anymore...it would be nothing more than an electric resistance heater or an exothermic chemical reaction (or a thermodynamically equivalent design). If by heat pump, you mean refrigeration cycle or air conditioning, where heat is trash instead of treasure, you MUST have a region for heat rejection, otherwise it would violate the second law of thermodynamics. To add stealth to a vehicle, you could accomplish this by storing the trash heat in an insulated vessel of water, and then replace said water when in a region where stealth is unimportant. If you want a refrigeration cycle to operate in an airless environment (on the moon or in interplanetary space), the ONLY method of accomplishing heat rejection is via a heat exchanger which operates with radiation on its outside, radiating waste heat to the background via naturally produced infrared of black body radiation.
