TEV cerrada.El compresor est parado.0.7 bar muelle

AC-RDM / FA / AKC 72 presentation

Arranca el compresorTEV comienza a abrir.4.7 bar4C4.70.73.1-6C3.1 barR223,1 bar Presin de evaporacin4.7 bar presin del bulbo0.7 bar muelleVlvula abriendo

AC-RDM / FA / AKC 72 presentation

La vlvula TEV abre ms.TEV abre del todo.4 bar0C-6C3.1 barR2240.73.14 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula abriendo

AC-RDM / FA / AKC 72 presentation

La TEV cierra de nuevo3.5 bar-3C-6C3.1 barR223.50.73.13,5 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula cerrando

AC-RDM / FA / AKC 72 presentation

LA TEV abre otra vez3.85 bar-1C-6C3.1 barR223.850.73.13,85 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula abriendo

AC-RDM / FA / AKC 72 presentation

La TEV vuelve a cerrar otra vez3.5 bar-3C-6C3.1 barR223.50.73.13,5 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula cerrando

AC-RDM / FA / AKC 72 presentation

La TEV trabaja con un recalentamiento constante3.8 bar-1,05C-6C3.1 barR223.80.73.13,85 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula con grado de apertura constante

AC-RDM / FA / AKC 72 presentation

TEV trabajando con una ligera reduccin de carga.3.79 bar-1.1C-6C3.1 barR223.790.73.13.79 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula cerrando un poco

AC-RDM / FA / AKC 72 presentation

TEV trabajando con un incremento de carga.3.85 bar-0.73C-6C3.1 barR223.850.73.13,85 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula abriendo

AC-RDM / FA / AKC 72 presentation

El compresor para,TEV cierra lentamente3.8 bar-1C-6C3.1 barR223.80.73.13,8 bar presin del bulbo0.7 bar muelle3,1 bar Presin de evaporacinVlvula cerrando lentamente

AC-RDM / FA / AKC 72 presentation

El compresor est parado,TEV an cierra.4.2 bar1C-3C3.5 barR224.20.73.54.2 bar presin del bulbo0.7 bar muelle3,5 bar Presin de evaporacinVlvula cerrando

AC-RDM / FA / AKC 72 presentation

El compresor est parado,TEV cerrada.4.5 bar3C-1C3.8 barR224.50.73.84.5 bar presin del bulbo0.7 bar muelle3,8 bar Presin de evaporacinVlvula en equilibrio

AC-RDM / FA / AKC 72 presentation

El compresor est parado,TEV cerrada con seguridad.4.7 bar4C4C4.7 barR224.70.74.74.7 bar presin del bulbo0.7 bar muelle4.7 bar Presin de evaporacinVlvula cerrada durante la parada

AC-RDM / FA / AKC 72 presentation

The compressor is not running.

The combined pressure balance and spring force keep the thermostatic expansion valve closed.

As it is a parallel charge in the sensor system the Pb and the Po equalize each other, so it is the spring force which keep the valve closed.

The room temperature is + 4 C.

The refrigerant is R-22. When the compressor starts the Po pressure is almost instantly reduced to the normal compressor suction temperature.

It means that the valve will open immediately and starting injection refrigerant into the evaporator.Because of the sudden drop in closing forces in the valve the valve will open too much.

Because of this the superheat is becomming too little and the valve starts closing again.

In fact the hunting during start up but will stabilize soon.The valve is now closed because of too little superheat to keep it in open position.

Now the valve will not inject refrigerant into the evaporator and the superheat will start to increase again.Now the superheat has increased so the valve is again open, but not so much as first time.

The opening is still enough to give a too big reduction in superheat so the valve will start closing again.The valve is now closed again, but the closing force is less that the first time.

So the hunting or swings are being reduced every time untill the valve finally will have a steady opening.

This steady opening will then corrospond to the heat load on the evaporator.The valve now have a steady opening and injecting the required amount of refrigerant to keep a steady superheat where the sensor is mounted.

Now the opening of the valve will not change very much.

It will only change little on opening of the cold room dor, switching light on and of, ect. (Minor load changes).The opening degree of the valve is lees than before.

Example could be winter, night time or colder ambient temperature during day time. This is day time operation again.

But to day some new goods or produce is coming into the cold room.

The goods or produce has a temperature above the room temperature.

So to cope with this load the valve has to open more to inject the required refrigerant to maintaine the superheat.When the compressor stops the suction pressure or temperature starts to increase.

The thermostatic expansion valve will start closing.

Refrigerant will still be injected into the evaporator.As it takes some time before the pressure/temperature has equalized fully, it also takes time for the thermostatic expansion valve to close.

In this slide no. 15 the pressures have equalized more than in slide no. 14, but the valve is still not fully closed.

Refrigerant will still be injected into the evaporator.In this slide no. 16 the pressures have now equalized to a point so the closing forces are are the same as opening force.

The valve is closed OK, but not yet positively.

Sufficient time has now passed so the pressure/temperature has equalized to a point, so the thermostatic expansion valve is closed.

In this slide no. 16 the pressures/temperatures have now equalized so the closing forces are at maximum.

Sufficient time has now passed so the pressure/temperature has equalized Completely, so the thermostatic expansion valve is positively closed.