[jeff5may]

1 bar of pressure is atmospheric pressure. At atmospheric pressure, your gauges will read 0 psi. Absolute pressure is at 0.000000X psi at a deep vacuum. This is what a micron gauge reads: microns of pressure above absolute zero. At atmospheric pressure, there is close to 15 psi of absolute pressure. The offset is much like the difference between degrees Kelvin and degrees Celsius. Water freezes way above absolute zero, at zero degrees Celsius.

A larger compressor is not going to make your evaporator behave much differently than it does now. The txv is serving two purposes: maintaining consistent superheat and limiting maximum suction pressure. When your evaporator gets cold, it will choke the flow so the compressor sees only superheated vapor. When the evaporator is warm, it limits evaporation pressure to keep the compressor cool. With a larger compressor, the evaporating pressure may actually drop compared to a smaller compressor with the same load conditions. This is because a larger compressor "sucks" more gas. Even though the txv may be opened further, the pressure may be a tad lower if the hx is working harder. With faster moving juice (higher flow rate), the txv knows to choke the flow, to force a colder, more heat hungry evaporator. These valves are a lot smarter than a cap tube.