Series
HRS
Cooling Capacity Calculation
Required Cooling Capacity Calculation
Example 1: When the heat generation amount in the customer’s machine is known.
The heat generation amount can be determined based on the power consumption or output of
the heat generating area — i.e. the area requiring cooling — within customer’s machine.
I: Current
(1) Derive the heat generation amount from the power consumption.
Power consumption P: 1000 [W]
Q = P = 1000 [W]
Cooling capacity = Considering a safety factor of 20%,
1000 [W] x 1.2 = 1200 [W]
V: Power
supply
voltage
Q: Heat generation
amount
Customer’s
machine
P
Power
consumption
(3) Derive the heat generation amount from the output.
(2) Derive the heat generation amount from the
power supply output.
Output (shaft power, etc.) W: 800 [W]
Power supply output VI: 1.0 [kVA]
W
Q=P=
Q = P = V x I x Power factor
Efficiency
In this example, use an efficiency of 0.7:
In this example, using a power factor of 0.85:
800
= 1.0 [kVA] x 0.85 = 0.85 [kW] = 850 [W]
=
= 1143 [W]
0.7
Cooling capacity = Considering a safety factor of 20%,
Cooling capacity = Considering a safety factor of 20%,
850 [W] x 1.2 = 1020 [W]
1143 [W] x 1.2 = 1372 [W]
The above examples calculate the heat generation amount based on the power consumption.
The actual heat generation amount may differ due to the structure of customer’s machine.
Please be sure to check it carefully.
Example 2: When the heat generation amount in the customer’s machine is not known.
Obtain the temperature difference between inlet and outlet by circulating the circulating fluid inside the customer’s machine.
Heat generation amount by customer’s machine Q : Unknown [W] ([J/s])
Circulating fluid
: Clear water
Circulating fluid mass flow rate qm
: (= R x qv ÷ 60) [kg/s]
Circulating fluid density R
: 1 [kg/dm3]
Circulating fluid (volume) flow rate qv
: 10 [dm3/min]
Circulating fluid specific heat capacity C
: 4.2 x 103 [J/(kg·K)]
Circulating fluid outlet temperature T1
: 293 [K] (20 [oC])
Circulating fluid return temperature T2
: 295 [K] (22 [oC])
Circulating fluid temperature difference @T
: 2.0 [K] (= T2 – T1)
Conversion factor: minutes to seconds (SI units) : 60 [s/min]
Refer to page 57 for the typical physical property value of clear water or other
circulating fluids.
Q = qm x C x (T2 – T1)
=
R x qv x C x @T
1 x 10 x 4.2 x 103 x 2.0
=
60
60
Cooling capacity = Considering a safety factor of 20%,
1400 [W] x 1.2 = 1680 [W]
Thermo-chiller
qv: Circulating Q: Heat
fluid flow
generation
rate
amount
Customer’s
machine
@T = T2 – T1
T1: Outlet temperature
56
Heat generation amount by customer’s machine Q : Unknown [cal/h] m [W]
Circulating fluid
: Clear water
Circulating fluid weight flow rate qm
: (= R x qv x 60) [kgf/h]
Circulating fluid weight volume ratio G
: 1 [kgf/L]
Circulating fluid (volume) flow rate qv
: 10 [L/min]
Circulating fluid specific heat capacity C : 1.0 x 103 [cal/(kgf·oC)]
Circulating fluid outlet temperature T1
: 20 [oC]
Circulating fluid return temperature T2
: 22 [oC]
Circulating fluid temperature difference @T : 2.0 [oC] (= T2 – T1)
Conversion factor: hours to minutes
: 60 [min/h]
Conversion factor: kcal/h to kW
: 860 [(cal/h)/W]
Q=
= 1400 [J/s] z1400 [W]
T2: Return
temperature
Example of conventional measurement units (Reference)
=
qm x C x (T2 – T1)
860
G x qv x 60 x C x @T
860
1 x 10 x 60 x 1.0 x 103 x 2.0
860
1200000 [cal/h]
=
860
=
z1400 [W]
Cooling capacity = Considering a safety factor of 20%,
1400 [W] x 1.2 = 1680 [W]
Cooling Capacity Calculation
Series
HRS
Required Cooling Capacity Calculation
Example 3: When there is no heat generation, and when cooling the object below a
certain temperature and period of time.
Heat quantity by cooled substance (per unit time) Q : Unknown [W] ([J/s])
Cooled substance
: Water
Cooled substance mass m
: (= R x V) [kg]
Cooled substance density R
: 1 [kg/L]
Cooled substance total volume V
: 20 [dm3]
Cooled substance specific heat capacity C
: 4.2 x 103 [J/(kg·K)]
Cooled substance temperature when cooling begins T0 : 305 [K] (32 [oC])
Cooled substance temperature after t hour Tt
: 293 [K] (20 [oC])
Cooling temperature difference @T
: 12 [K] (= T0 – Tt)
Cooling time @t
: 900 [s] (= 15 [min])
Refer to the following for the typical physical property values by circulating fluid.
m x C x (Tt – T0)
R x V x C x @T
=
@t
@t
1 x 20 x 4.2 x 103 x 12
=
= 1120 [J/s] z 1120 [W]
900
Q=
Cooling capacity = Considering a safety factor of 20%,
1120 [W] x 1.2 = 1344 [W]
Thermo-chiller
Example of conventional measurement units (Reference)
Heat quantity by cooled substance (per unit time) Q : Unknown [cal/h] m [W]
Cooled substance
: Water
Cooled substance weight m
: (= R x V) [kgf]
Cooled substance weight volume ratio :
: 1 [kgf/L]
Cooled substance total volume V
: 20 [L]
Cooled substance specific heat capacity C : 1.0 x 103 [cal/(kgf·oC)]
Cooled substance temperature when
cooling begins T0
: 32 [oC]
Cooled substance temperature after t hour Tt : 20 [oC]
Cooling temperature difference @T
: 12 [oC] (= T0 – Tt)
Cooling time @t
: 15 [min]
Conversion factor: hours to minutes
: 60 [min/h]
Conversion factor: kcal/h to kW
: 860 [(cal/h)/W]
Q=
: x V x 60 x C x @T
m x C x (Tt – T0)
=
@t x 860
@t x 860
1 x 20 x 60 x 1.0 x 103 x 12
15 x 860
z 1120 [W]
=
Q x @t: Heat volume [kJ]
Water bath
20oC
Cooling capacity = Considering a safety factor of 20%,
V
1120 [W] x 1.2 = 1344 [W]
After 15 minutes, cool 32oC down to 20oC.
Note) This is the calculated value by changing the fluid temperature only.
Thus, it varies substantially depending on the water bath or piping shape.
Precautions on Cooling Capacity Calculation
1. Heating capacity
When the circulating fluid temperature is set above room temperature, it needs to be heated by the Thermo-chiller. The heating capacity depends on the
circulating fluid temperature. Consider the radiation rate and heat capacity of the customer’s machine and check beforehand if the required heating
capacity is provided.
2. Pump capacity
<Circulating fluid flow rate>
Circulating fluid flow rate varies depending on the circulating fluid discharge pressure. Consider the installation height difference between the
Thermo-chiller and a customer’s machine, and the piping resistance such as circulating fluid pipings, or piping size, or piping curves in the machine.
Check beforehand if the required flow is achieved, using the pump capacity curves.
<Circulating fluid discharge pressure>
Circulating fluid discharge pressure has the possibility to increase up to the maximum pressure in the pump capacity curves. Check beforehand if the
circulating fluid pipings or circulating fluid circuit of the customer’s machine are fully durable against this pressure.
1. This catalog uses the following values for density and specific heat capacity in calculating the required cooling capacity.
Density
Specific heat capacity
R: 1 [kg/L] (or, using conventional unit system, weight volume ratio : = 1 [kgf/L ] )
C: 4.19 x 103 [J/(kg·K)] (or, using conventional unit system, 1 x 103 [cal/(kgf·oC)])
2. Values for density and specific heat capacity change slightly according to temperature shown below. Use this as a reference.
Water
15% Ethylene Glycol Aqueous Solution
Physical property
value
Temperature
5oC
10oC
15oC
20oC
25oC
30oC
35oC
40oC
Conventional unit system
Density R Specific heat C
[kg/L]
[J/(kg·K)]
Weight volume ratio : [kgf/L] Specific heat C [cal/(kgf·oC)]
1.00
1.00
1.00
1.00
1.00
1.00
0.99
0.99
4.2 x 103
4.19 x 103
4.19 x 103
4.18 x 103
4.18 x 103
4.18 x 103
4.18 x 103
4.18 x 103
1.00
1.00
1.00
1.00
1.00
1.00
0.99
0.99
1 x 103
1 x 103
1 x 103
1 x 103
1 x 103
1 x 103
1 x 103
1 x 103
Physical property
value
Temperature
5oC
10oC
15oC
20oC
25oC
30oC
35oC
40oC
Conventional unit system
Density R Specific heat C
[kg/L]
[J/(kg·K)] Weight volume ratio : [kgf/L] Specific heat C [cal/(kgf·oC)]
1.02
1.02
1.02
1.01
1.01
1.01
1.01
1.01
3.91 x 103
3.91 x 103
3.91 x 103
3.91 x 103
3.91 x 103
3.91 x 103
3.91 x 103
3.92 x 103
1.02
1.02
1.02
1.01
1.01
1.01
1.01
1.01
0.93 x 103
0.93 x 103
0.93 x 103
0.93 x 103
0.93 x 103
0.94 x 103
0.94 x 103
0.94 x 103
Note) The above shown are reference values. Please contact circulating fluid
supplier for details.
57
Related
Products
Technical
Data
Circulating Fluid Typical Physical Property Values