Evaporator sizing - is bigger better?

[Acuario]

Now I have my defrost circuit monitoring the temperature on both sides of my evaporator I got to thinking, would a bigger evaporator be more efficient?

Heat pumps obtain their energy from low grade heat (the atmosphere) and 'convert' it into high grade heat using a compressor. The warmer the temperature of the gas entering the compressor the less hard the compressor has to work to compress the gas and raise its temperature.

Whilst monitoring my evaporator I have seen variations of temperature difference of between 1C and 6C depending on the ambient temperature. The exit temperature is invariably less than ambient temperature (it approaches it at very low temperatures).

So, my thought is, with a larger evaporator there would be extra surface area (and time) for the refrigerant to absorb heat from the atmosphere, hence improving the efficiency of the heat pump.

Has anyone tried this? The argument seems sound but does it work in practice?

I have a machine with a dead compressor but a perfectly serviceable fan and evaporator and I'm tempted to try it out but would love to hear any feedback on my proposed hack before getting out the cutters and brazing torch.

Acuario