View Full Version : Can heat pumps be stepped up ?

14-07-2014, 12:32 PM
Hi all,

Please excuse me if my question seems dumb this is not my area of expertise.

My question refers to the refrigerant, currently the refrigerant acquires heat from temps as low as 258(K) and produces up to 328(K) in the cylinder. Could there be a secondary pump that acquires heat from the cylinder 328(K) and produces higher temps. From my limited knowledge, the boiling point of the refrigerant is related to the outside temps.

What would happen if a secondary system was installed using a liquid that boils at say 318(K) ?

Could this be installed inside the initial cylinder ?

If this is possible how many steps would be needed to reach 373(K) ?

How big would the external radiator need to be to heat 100ml of water to 373(K) ?

Live long and prosper!

The Viking
14-07-2014, 02:22 PM
Hi Goldy,

Yes, what you are describing is known as a cascade system.

How many steps and what efficiency depends on your application and refrigerant(s) used.

As to your question of how big the "external radiator" needs to be... How long is a piece of string?
In a void without heatlosses even 1W will eventually heat your water up, we therefore need to know the time frame, expected losses and starting temperature of the water (I sort of assume here that the water doesn't start at 0K). When you know that you can start to look at duty required and efficience, then and only then will you be able to size your evaporator/ heat collector.


15-07-2014, 01:42 PM
Hi Viking,

Thank you for your response.

I am working backwards from my model steam engine, 100ml water, candle and off she goes. I was just wondering if I could replace the candle with insulation and an internal heat element. My aim is to generate electricity, if a cascade system could reach 100C then steam could push a turbine and replace nuclear power :D eventually. I am sorry if my understanding is confused but my brain keeps asking questions.

Why don't we push turbines with refrigerant? Would the temp needed to create the pressure not be lower?

Live long and prosper!