Actual air-conditioning operation and its cycle

[narongwit12]

Dear all,

As many books and sources describe the refrigerant cycle at steady state for air-condition system, It really make me curious how the cycle change in the actual situation. So there are some questions, which it would be very kind of you if you could explain me how it actually take place :

1. According to some literatures, some refers to the condenser and evaporator temperature as fixed temperature, while some indicate it by varying it related to ambient condition. So, in actual situation, how is it?

2. Please correct me if i am wrong, as long as i am concerned, if the load is identical to that of design condition, the cycle should remain what it has been designed in the first place. And when the load is less than the design condition, the flow rate of refrigerant is reduced by inverter, et al. And if i am not wrong, the maximum compressor power is considered as constant.

3. In case of the actual condition is more extreme than what design condition is considered(Outdoor condition is extremely high, very large load), it would be very kind of you if you could explain what happen in the refrigerant cycle. Is it correct to assume that the heat gained from extreme conditions will raise the pressure or temperature in condenser and evaporator up?

Thank you in advance

Best regards
Areemit Narongwit

[NoNickName]

1. According to some literatures, some refers to the condenser and evaporator temperature as fixed temperature, while some indicate it by varying it related to ambient condition. So, in actual situation, how is it?

Devices on board will try to keep the temperatures as constant as possible, while in practice they vary with non-linear physics. TXV will try to keep SH as constant as possible, but evaporation temperature increases as the medium temperature increases (air or water, whatever), the condensing control (if installed) will try to keep the condensing pressure as constant as possible. Besides, the real working conditions can be higher or lower than the max and min range of regulation, and can even take advantage of cut-off for low pressure.



2. Please correct me if i am wrong, as long as i am concerned, if the load is identical to that of design condition, the cycle should remain what it has been designed in the first place.

Yes.



And when the load is less than the design condition, the flow rate of refrigerant is reduced by inverter, et al. And if i am not wrong, the maximum compressor power is considered as constant.

No. First of all, inverters are not always installed, and at the moment they represent a minor fraction of the total number of conditioners and chillers installed.
The maximum power is not constant with inverters, but decreases as frequency decreases.
In a non.inverter driven chiller, the cooling capacity is either reduced with unloading or with cycling.



3. In case of the actual condition is more extreme than what design condition is considered(Outdoor condition is extremely high, very large load), it would be very kind of you if you could explain what happen in the refrigerant cycle.

The condensing pressure will progressively increase as more kW are to be rejected in the condenser. Eventually the unit will stop by high pressure.



Is it correct to assume that the heat gained from extreme conditions will raise the pressure or temperature in condenser and evaporator up?

It is.

[narongwit12]

Thank you very much. Your suggestion is greatly invaluable to me.

Areemit Narongwit

[muhammad ali]

what kind of cooler we use in dx air conditioning?

[Brian_UK]

what kind of cooler we use in dx air conditioning?
- - - dx - - -

[james10]

- - - dx - - -

:d:d:d:d:d

[Brian_UK]

^^James, you need to use a Capital D not lower case d.