Chiller Cooling Capacity – How to calculate

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How to calculate the cooling capacity of a chiller. Chillers provide chilled water which is then used to provide air conditioning within buildings. The amount of cooling they produce varies and it’s important to know how much cooling a chiller is producing or is able to produce. There is a video tutorial at the bottom of the page also.

Firstly to perform this calculation we need to know a few things.

• The volume flow rate of water into the evaporator
• The inlet and outlet chilled water temperature

We then need to lookup the properties of water for the following

• The density of the water at the average temperature (inlet temp + outlet temp)/2
• The Specific Heat Capacity of the chilled water at the average temperature (inlet temp + outlet temp)/2

A recommended website to look these properties up is: PeaceSoftware.de

Let look at how to calculate the cooling capacity. We’ll first look at how to calculate in metric units and then imperial.

Metric units:
The water flow rate of chilled water into the evaporator is 0.0995m3/s, the inlet temperature is 12*c and the outlet temperature is 6*c. This means the average temperature is 9*c so we lookup the water properties at this temperature to find the density of 999.78kg/m3 and a specific heat capacity of 4.19kJ/kg/K.

Using the energy equation of Q = ṁ x Cp x ΔT we can calculate the cooling capacity.

Q = (999.78kg/m3 x 0.0995m3/s) x 4.19kJ/kg/K x ((12*c+273.15K) – (6*c+273.15K))

We add 273.15K to the celcius to convert it to units of Kelvin. The Specific heat capacity (Cp) is measured in units of kJ per kg per Kelvin.

This gives us a final answer of Q = 2,500kW of cooling. Full calculations are shown below. Now lets look at how to calculate the cooling capacity of a chiller in imperial units

Imperial units:

The flow rate of chilled water into the evaporator is measured as 12,649ft3/h and the chilled water inlet temperature is 53.6*F the outlet temperature is 42.8*F. The average temperature is 48.2*F so we need to calculate the water properties at this temperature.

A good website for this is peacesoftware.de the although we will need to convert the units to imperial so for that we will use Specific heat capacity and density of water

This will give us a specifi heat capacity of 1.0007643BTU/lb.F and density of 62.414lb/Ft3

Using the energy equation of Q = ṁ x Cp x ΔT we can calculate the cooling capacity.

Q = (16,649FT3/h x 62.414lb/ft3) x 1.0007643BTU/lb.F x (53.6F – 42.8F)

Giving us a cooling capacity of 8,533,364BTU/h. see full calculations below.

1. Tony

Hi Paul,
Good day. Need your advice on heat recovery system from water chiller to heat water in building for hot water supply. Requirement parameters are:
1) heat circulating water from ambient inlet 27 degC to supply outlet 60 degC;
2) current chiller design 35 kW;
3) chilled water supply inlet 14.8 degC and return outlet 8 degC.
Please advise with justification/calculations if this system chiller is able to perform to its requirements.
(Hot water supply to roof storage tanks usage 12 cu.metres per day)

Also, the heat loss on a 50mm diameter with 25mm insulation over a distance from chiller to roof storage tanks is est. 100m in length. What’s the possible heat loss?

Appreciate for prompt reply Paul. Thank you & cheers.

Best regards,
Tony

2. hassan

hi
good day,
please calculate pressure or temp for compression refrigeration cycle 7kw?(r-134a)
later than i know 7kw
i want to know how i calculate comp cond evap.

3. Koh

Hi,

Like to ask. For instance a chiller is connected to 4 AHU. IF I manage to use analytics to understand my actual demands and use it to reduce the chill water flow rate and optimise the delta temperature of chill water inlet and outlet at AHU level, and save an average of 30% energy saving using btu meters measure at the 4 ahu chill water.

Does saving this 30 % energy of chill water Meanthat I could be saving 30% energy or more of the whole hvac system (chiller, compressor, pump)? Reason for having this assumption is if my chill water temperature and flow is optimise, my chiller will work lesser to produce the output which is chill water.

Am I right in this assumption?

4. KAPALA

Hello dear Mr. Paul have a nice day.

5. Ishu

Hii I wish to know how much water temperature outlet and how inlet in chiller

6. deepak chawla

Hello sir,
i have a chiller 260 tr if chiller running 12 hours per days , it is possible may we count line loss kwh to kwah, and reply for minimum line loss.

7. Rohit

Sir how to confirm chiller how much tr
Formula

8. Faheem

Hi Sir,

Can u suggest me suitable flow meter to measure the flow rate of Air Cooled 240 TR Chiller.

Line size is 6 inch

9. sanoop

how to calculate transformation lose of ammonia chiller

10. manohar

How to select pipe size for chiller line if pump capacity known..

11. Mech

what if the water is 25% glycol based? how to identify the density & Cp in this condition? do you have any website where we can verify it? like you mentioned for the water ‘peacesoftware.de’

12. Alexander

I am trying to figure out my chillers cooling capacity at variant outlet temperatures, while maintaining the same ambient temperature. For example, I have a low temperature chiller that provides 5RT (60,000 Btu)at a leaving temperature of 5°F while at 95°F ambient temperature
how can I calculate its cooling capacity at 10°F, 20°F, 30°F 40°F outlet temperatures.

13. Gautham

50kw liquid chiller unit:
For above chiller how much air flow required for gud efficiency. As well as how to calculate the aluminum finned type heat exchanger. Please suggest use.

14. Alfano Rick

So I’m on a chilled water system in my condo. The water originates from a well in the ground and returns to after running through the air handlers. Does the water run around the coils? Do you have a diagram. Is there a wat to clean the coils that the well water runs through

15. Alfano Rick

So I’m on a chilled water system in my condo. The water originates from a well in the ground and returns to the well after running through the air handlers. Does the water run around the coils? Do you have a diagram. Is there a way to clean the coils that the well water runs through

16. ajay k

Hii paul, thanks for explaining in detail, can you please tell us the working of economizer in a chiller unit.

17. sergio lopez

Hi, is there a typo in the metric calculation of BTU/hr? it shows 8xx,xxx.xx instead of 8 million xxx. Or am I missing something?

18. Vishal

Hi I am Vishal my question if 150TR compreesor how much ampere load it takes