Compressor sizing using R404a

:confused: Hi all,

I would like to seek advise on sizing the reciprocating compressor (Carlyle brand). Base on the Heat Load Calculation, the sensible and latent heat gain is about 100kW. Using the psychrometric chart, my required cooling capacity is about 300kW.

I have problem trying to determine refrigerant data such as, the Saturated suction temperature, liquid temperature before and after condenser etc temp related data.

I assume I would need these data to determine the mass flow of refrigerant and in order to determine the size of the compressor.

I have tried using the Carwin software for compressor sizing, however the software required the temperature data to size the compressor too.

Please advise. Many thanks.

My advice is get a book.

Renato

Quote:

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Originally Posted by PCL

:confused: Hi all,

I would like to seek advise on sizing the reciprocating compressor (Carlyle brand). Base on the Heat Load Calculation, the sensible and latent heat gain is about 100kW. Using the psychrometric chart, my required cooling capacity is about 300kW.

I have problem trying to determine refrigerant data such as, the Saturated suction temperature, liquid temperature before and after condenser etc temp related data.

I assume I would need these data to determine the mass flow of refrigerant and in order to determine the size of the compressor.

I have tried using the Carwin software for compressor sizing, however the software required the temperature data to size the compressor too.

Please advise. Many thanks.

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Hi PCL:)

I will try and help you, but your knowledge is a bit basic in some areas:)

OK start at the start. What room temperature (dry bulb) do you want. For example 22 deg c with an evaportor Temperature Difference of (TD) of 6K AND a line loss of 2K due to pressure drop, then you Saturated suction would be 14 deg c. Now look at your latent heat load, if you want remove moisture from the air (you will normally need to for comfort). Saturation point or where you start to remove moisture is probably about 13 deg c (you will need your evaporation lower than this to remove moisture), possibly 8 deg c evaporation at the evaporator (this you will be able to determine on the psychrometric chart) that add a 2 deg link loss, giving you a compressor saturated suction of 6 deg c.

Now select you condensing tempearture 10k above ambient air say the air was 35 deg, add 1k line loss and your condensing temperature would be 46 deg c.

Subcooling,depends on you fridge design, but 3 k would get you started.

Let me know if this makes sense.

Kind Regards Andy:)

Andy has provided some information there.

I also think you have another issue that should be more important right now.

Quote:

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Originally Posted by PCL

Base on the Heat Load Calculation, the sensible and latent heat gain is about 100kW. Using the psychrometric chart, my required cooling capacity is about 300kW.

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Your load calculation has a difference of 300%. That needs to be resolved before you worry about selecting compressors, etc.

Good Advice andy