need your help

[shsalameh]

Running an air cooled water chiller with two reciprocating compressors and R22 *****
get the followig
first circuit - full load:
- Ambient temp: 29 C
- lvg evap water temp: 6.5 C
- sat evap temp: -2 C
- Sat cond temp: 50 C
- Superheat: 5 C
- Subcool: 10 C
- Discharge temp: 88 C

Second circuit - full load:
- Ambient temp: 29 C
- lvg evap water temp: 6.5 C
- sat evap temp: 0 C
- Sat cond temp: 50 C
- Superheat: 5 C
- Subcool: 10 C
- Discharge temp: 76 C

* is sat evap temp low for cir-1?
* is disch temp high for cir-1?
* is subcool high for both cir
* is evap approach and cond approach high for both cir.

thank you

[chemi-cool]

Hi Sharif,

What is the entering water temp?

Can you give the pressures as well,


Chemi

[shsalameh]

Hi Chemi;

- entering water temperature for both circuits = 12.5 to 13 C
- Cond pressure for both circuits = 18.5 to 19 bar
- evap sat press cir-1 = 4.3 bar
- evap sat press cir-2 = 5 bar

Thank you

[Vincent Yu]

When I design an air cooled chiller with plate evaporator, normally the condensing temperature is 25F higher than ambient temperature, and the evaporating temperature is 10F lower than outlet water temperature. Although I cannot prove it, I feel under these conditions, the system is price efficient. If I were you, I would select evaporating temperature = 0 C and the condensing temperature = 43 C ~ 45 C. Please let me know if anyone has good ideas to select condensing and evaporating temperatures.

Under the condition the evaporating temperature is 0 C, condensing temperature is 45 C, 10 C subcooling, 5 C superheat, compressor isentropic efficiency is 0.7, no pressure losses in suction line and discharge line, no compressor heat loss, and no suction line unuseful superheat, the discharge temperature should be 68.4 C.

[Gary]

On the condensers, what are the entering and leaving air temperatures?

[chemi-cool]

Hi Gary,

its easy to find the answer to your question,

normally the condensing temperature is 25F higher than ambient temperature,

Dont you think?

Chemi

[patrickj]

Running an air cooled water chiller with two reciprocating compressors and R22 *****
get the followig
first circuit - full load:
- Ambient temp: 29 C
- lvg evap water temp: 6.5 C
- sat evap temp: -2 C
- Sat cond temp: 50 C
- Superheat: 5 C
- Subcool: 10 C
- Discharge temp: 88 C

Second circuit - full load:
- Ambient temp: 29 C
- lvg evap water temp: 6.5 C
- sat evap temp: 0 C
- Sat cond temp: 50 C
- Superheat: 5 C
- Subcool: 10 C
- Discharge temp: 76 C

* is sat evap temp low for cir-1?
* is disch temp high for cir-1?
* is subcool high for both cir
* is evap approach and cond approach high for both cir.

thank you

DEAR SHSALAMEH

bE CAREFUL YOUR CHILLER IS REACHING THE DANGER ZONES TOO CLOSE TO FREEZING.Cooler approaches are not good enough, suction low discharge temperatures too high.

patrickj

[Lc_shi]

from the data,the evap temp is lower. I'm not sure if you add anti-freezing liquid in the water. I think the evap temp should be around 2C. Verify the water volume and check the ampere of the compressor to see if the charge is a little less which may increase the dischange temp? only for your ref.

lichuan

[Gary]

Hi Gary,

its easy to find the answer to your question,


Dont you think?

Chemi

Enlighten me.

[Gary]

I'm wondering if the evaporators are counterflow as they should be, or parallel flow, as they appear to be not picking up a full heat load and are showing a high approach temperature.

On the other hand, the condensers appear not to be able to handle the heat load they currently have, much less a full heat load.