Thermodynamic panels

I've not seen anything on this type of technology for hot water (hydronic slab and hot water cylinder ).  They initially claimed a COP of 2 - 7 but independent testing says it's closer to 2 when tested on one system.

Basically it's a flat panel filled with refridgerant gas that's liquid at -20 deg C.  When exposed to heat above that it vapourises.  The 390W compressor squeezes the heat out of the gas returning it to liquid state and the heat is used to heat water up to a temperature of 55 deg C.  It can work day and night and when snowing, but works best when in the sun.

So, really the only maintenance is the compressor.  And if you have a PV panel to power the compressor, that lowers the cost of power so maybe that raises the COP?



The manufacturer is in Portugal https://www.energie.pt/en/

That looks cool.  So it's using a somewhat standard refrigeration cycle where the outside loop is picking up low grade heat (plus solar heating of the flat plate) and dumping it into a tank of water.  Kind of like an air source heat pump would if it heated water.

So it's an air to water heat pump where the evaporator unit uses the aluminium panel heated by the sun/environment instead of a fan.  So, even snow would transfer heat to the panel as the refrigerant is liquid at -30 deg C, and the panel functions down to -15 deg C.

These things operate better at higher temperatures.  Solar assisted heat pumps when heating water can reach a COP of 5.7 (vs immersion heaters which are less than 1)  So, I wonder how much improvement one would get by building a solar hot air collector and blowing the resulting hot air over the thermodynamic panel.  The power for the fan could come from a PV panel or battery when there's not enough sun.

Or embedding the panel in the mass of a tiny RMH....

Not sure about that.  There must be a heat transfer rate limit ... any refrigeration engineers here?

This looks like a simple heat pump in concept. But a concept is made real as a product - products are complex haystack of compromises which bring them into the "real world". Meaning there's no such thing as a free lunch. Especially in thermodynamics mated with complex technology..

Any particular compressor?

With proper assembly, the piping might be relatively maintenance free - depending on the environment. But because the system needs to absorb solar heat as efficiently as possible and the surfaces of and in the solar modules would likely be suffer functional problems from corrosion and dirt over time, the solar modules would have a definite life cycle. To say nothing of the coils in the water tank.

The compressor and the various sensors and switches need maintenance like any other appliance. Technology needs various control systems meaning circuit boards, connectors, relays, etc. All degrade yearly.

Not to say a simple heat pump is a bad idea. But this type of wheel has not only been invented, myriad examples are already out there running around in the present market place. Where is the advantage this particular company is selling? Do they have competitors and if not why not? There _should_ be competitors out there...

This may or may not be a good product, but the simple thermodynamic concept doesn't begin to explain the whole situation.


Rufus

From what I can tell the design advantage over a standard heat pump for hot water is the larger panel, the solar assist, and the loss of the fan that would normally pull air across the panel.