Suction Pressure setting in respect of Evaporator temprature

[pradeepgh]

Hi!
Can anyone help to proivde the data to set the suction pressure at different temp of R-134 A.
Basically during breakdown of freezer in -temp the temp of evaporators are different at the time of recification due to which the refrigerant not charged properly and on proper cooling the refigreant required to add or release from the system.The temp in the cabinet take time and it is difficult to remain at site for so long time.

[Balakathiresan]

Hi,
Properties of refrigerants at saturated conditions should be available in all Refrigeration handbooks, ASHARE Fundamentals, etc

[The Viking]

Sorry but there is a major flaw in your question.

What you have to look at is the relationship between the pressures inside the system and the temperatures.

As said above, a quick websearch will give you the info you asked for, HERE (http://www.csgnetwork.com/r134apresstempconv.html) is one example but that alone will not tell you anything about the charge in the system.

:cool:

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[pradeepgh]

My querry is
In a system where the required temparature in cabinet is -18 deg.The units goes breakdown and we required to charge the refigerant when the cabinet temprature goes down at different temp. eg -5 Deg. or may be + temp.The desire temp wil be take time to reach.What amount of suction pressure will be set in system at different inside temprature to fix the system without waiting for long time.

[Balakathiresan]

To attain -18°C at inside cabinet, the refrigerant evaporation temperature should be less than -20°C. This again based on manufacturer's heat exchanger design.

[The Viking]

To achieve what you are looking for, i.e. the correct charge in the system, you will have to look primarily on the sub cooling. This is the difference between the dewpoint of the refrigerant at the discharge pressure and the actual liquid line temperature.

Depending on actual design of your units this might vary slightly with cabinet temperature but if it is charged up to 8-10K at room temperature you are probably not far off. After you have got the system down to temperature you could compare the values, then you would know for next time...

:cool:

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