Ok so a little background on the phase change heating and cooling system first.
Any air conditioning or heating system that relies on the phase change system moves heat via mass flow of refrigerant. More mass flow equals more heat flow. Every other variable in the system that affects performance performance affects mass flow.
The phase change of refrigerant (liquid to gas absorbs heat, gas to liquid releases heat) is where most people encounter difficulty when trying to understand the system. This is the "magic" of the system. It's pretty well explained in this thread:
https://ecorenovator.org/forum/showthread.php?t=3160
The main difference between a DX loop and indirect exchange is the efficiency gain of not having a pump that robs power from the overall efficiency of the system. Other potential advantages are:
- heat exchanger maintenance near zero
- no intermediate heat transfer media to bottleneck heat flow