Expansion Valve Damping Effect!!!

[bjkmiami]

Hi everyone!!!
what is expansion valve damping effect and hunting effect?? what needs to be done to reduce??
thx

[Tesla]

Hi bjkmiami
damping is a slowing down of the response to an effect which will cause a change in the valve position - a bit like the air in the tyres of a car dampening the pot hole bump. A spring inside the TEV is used for this effect.
Hunting is when the valve drives past the optimum position for smooth (1/4 amplitude decay) control. Like when I learnt to drive a car I bunny hopped with full gas then no gas repetitively causing the car to go stop go stop - you get what I mean. The valve will not find a "sweet spot" where it matches the load and causes too mech then too little refrigerant flow and repeating. In this case the valve spring is adjusted to increase/decrease dampening and bring the system into control.
Any question s on this just let me know and I will try to explain further. It is a little easier to understand once you have done a few calculations with spring pressure, bulb pressure and evap pressure on the bellows. Also help to see it out in the field with a god fast temp sensor where the bulb is and a pressure gauge to measure the superheat. It is a dynamic process.