A guidance for industrial chiller sizing, might be useful if you are facing such a problem

1. How to correctly size an industrial chiller?
The purpose of an industrial chiller is to cover the heat load generated by the
production process, so to keep the temperature within your required range,
therefore the first thing to correctly size a chiller is that you need to know the
heat load of your production process. However, to make sure a chiller
suitable for your application, we need to do more. For example, is air cooled
or water cooled chiller suitable for your case? Do you need open circuit or
close circuit chiller? As a chiller manufacturer and cooling solution provider, it
is our responsibility to help our user to size a chiller that serves their demand.
I. Calculation of required cooling capacity
We could always calculate the heat load by the thermodynamic basic formula
Q=c*m*△t, Q: heat load, c: specific heat of the object need to cool, m: weight
of the object, △t: temperature difference(between the target temperature and
initial temperature). However, for most applications which use chiller
frequently, there must be a simpler way to get a result more conveniently.
Here are some advices from Senho engineers:
Note: the below solutions is for reference for regular applications only
1. Plastic&rubber industry
a. Extrusion, blow molding, bottle blowing and film blowing
Formula: Q(Kcal/h)=Productivity(Kg/h)*165

2. This formula is actually simplified from the thermodynamic basic
formula, let’s see how it comes:
Based on Q=C*M* t, it seems all the conditions on the right side of
the equation are unknown. But regular plastic processing has its own
feature, for example, specific heat of plastic material is normally
below 0.55Kcal/h, the process temperature difference does not
exceed 200 in most applications. In this case, we could put these
values into the formula, it becomes:
Q=0.55Kcal/h*m*200 =m*110
As we know cooling capacity of a chiller is not constantly the same, it
changes with evaporating temperature and condensing temperature,
which means changing of working condition might cause fluctuation
of the performance of chiller unit. On the other hand, the heat
exchanging efficiency of the cooling spot is different to some extent.
Hence we need to put a safety value into this formula to enlarge its
error-tolerant rate, so we will enlarge the result by 50%, which makes
the formula into:
Q=0.55Kcal/h*m*200 *1.5=m*165
b. Injection molding(does not include PET preform)
The volume of plastic material an injection molding machine can
process depends on its clamping force, clamping force is somehow

3. related to the heat load the machine generated. We all know that an
injection molding machine is for process different plastic material any
time, as long as the mould is changed accordingly. On the other
hand, the cooling efficiency is influenced by the design of mould in
some way. For these reasons, sizing of chiller for injection molding is
somehow estimated, the bottom line is we need to make sure the
chiller capacity is adequate no matter how the products changes.
In most cases, 80Ton clamping force requires 2150Kcal/h cooling
capacity, which bring us the formula:
Q=Clamping force(Ton)/80Ton*2150Kcal/h
For example, we have one injection molding machine with 1000Ton
clamping force. Calculation as below:
Q=1000Ton/80Ton*2150Kcal/h
=26875Kcal/h
c. PET preform

4. PET preform is special in injection molding area, as it process only
one kind of material. Same as other processes, the heat load comes
from the hot material when it first came into the mould. In most cases
we need to calculate the productivity, i.e. how many KG material
does it process in one hour.
We will firstly learn how many cavities are there in one mould, what
is the weight of each preform, and what is the molding cycle time.
With these three conditions, we can easily learned the productivity by
kg/h.
For example, a PET mould with 32 cavities, each preform weigh 60g,
and mould cycle time is 5 seconds. Let’s see how to calculate:
60g*32*(3600s/5)=1,382,400g=1384.2kg
With productivity, we need to know the process temperature
difference, that is the temperature difference between PET material
when it comes into the mould and the temperature we need to bring
down to. For example, the hot PET temperature is 260 , we need to
cool the mould at 15 . We can easily use the formula Q=c*m* t
Q=c*m* t*1.5
=1384.2kg/h*0.53Kcal/(kg )*(260 -15 )*1.5
=269,607Kcal/h
Remarks: Specific heat of PET: 0.53Kcal/(kg ), safety factor: 1.5
2. Other industries
The formula Q=C*M* t is universal in the world of thermal energy. The
question is, how do we know the conditions on the right side of the
equation. In most cases we don’t know the C of the material we

5. process, we don’t know exactly the t as well, that’s what put us into
trouble.
No matter what material or equipment we need to cool, we will cool it
with water, or water with additive. So we can simply change our mind,
we calculate the heat load of water instead. Here are the steps:
Step 1: Get the flow rate
For an equipment that need to use cooling water, the manufacturer will
normally provide the requirement of cooling water flow. We can use the
figures provided or use a flowmeter to get what we need.
Step 2: Get the temperature difference
Please note that the temperature difference is between the inlet to your
equipment and outlet from your equipment. Please see the diagram
below, what we need is B minus A.
For this step, we can use an infrared radiation thermometer like
below

6. Step 3: calculation
After we get both flow rate and temperature difference, we can put it
into the formula: Q=c*m* t. For example, the flow rate we get is 5m
/h, temperature difference is 4 . As we know that C: specific heat of
water=4.187Kj/kg , we can start our calculation:
Q=c*m* t
=4.187Kj/kg *5000kg/h*4 *1.5
=83740Kj/h
=30008.24Kcal/h
Note: specific heat of water: 4.187Kj/kg , 5m water=5000L=5000kg, safety factor: 1.5
II. Water cooled or air cooled?
First we need to learn the difference of water cooled and air cooled chiller.
Please view here.
Then let’s see what do we need to consider:

7. 1. Do you have an open and drafty place for locating air cooled chiller? Or
you want to put your chiller indoor? If you want to put it indoor, water
cooled chiller will be the choice.
2. Do we have workers in charge of chiller maintenance, so the condenser of
water cooled chiller could be clean at intervals? If the water cooled
condenser is not clean for a long time, the chiller’s cooling efficiency will go
lower and lower.
3. Is water easily available in your area? Because for a water cooled chiller,
condenser water will somehow loss in the cooling tower, as most cooling
towers are open type. If water is not easily available, let’s consider air
cooled chiller.
In a word, both advantages and disadvantages of water cooled or air
cooled chiller are relative. To choose air cooled or water cooled chiller, you
need to consider your own conditions.
III. Open circuit or close circuit chiller?
When we talk about open circuit or close circuit here, we mean the chiller, not
the whole water circuit.
Now you need to consider your situation:
1. Do you have a reservoir for the cooling circuit already? If yes, let’s choose
close circuit chiller.
2. Is the water channel in your equipment close type? We need to pay
attention if there is already water tank or water sink in your equipment. For
example, some pipe extrusion machine is with water sink for the products
to immerse in, the chiller’s job is to cool the water in the sink, in this case
we need a close circuit chiller.
IV. Need non-corrosive water circuit?

8. For some industries such as laser, food and beverage, deionized water or
drinking water is required. Other industries like electroplating, the liquid is
corrosive itself. In those case, please let us know so that we can make sure
the water circuit of chiller is non-corrosive.
V. Need high water pressure?
In some case, your equipment needs high inlet water pressure, or the
distance, especially vertical distance is long between chiller location and your
equipment. Regular pressure is not suitable for those cases, then you need to
tell us about these conditions for correctly sizing.
In a word, it is important to know the working condition before sizing an
industrial chiller. A correctly sized chiller unit can make your production
process more fluency, and avoid many follow-up problems, so to increase the
efficiency of production.