SMC Networks HRL Series, Manual, Page: 22 / 28

HRL
Series
Cooling Capacity Calculation
HRL200-A
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 : (=
ρ
x V) [kg]
Cooled substance density
ρ
: 1 [kg/L]
Cooled substance total volume V : 250 [L]
Cooled substance specific heat C : 4.186 x 10 3 [J/(kg·K)]
Cooled substance temper ature when cooling begins T
0
: 305 [K] (32 [
°
C])
Cooled substance temper ature after t hour T
t
: 293 [K] (20 [
°
C])
Cooling temperature difference T : 12 [K] (= T
0 –
T
t
)
Cooling time t : 900 [s] (= 15 [min])
∗
Refer t o th e following for t h e typical p h ysical property values by circulatin g flui d.
Q = =
= = 13953 [J/s]
≈
14.0 [kW]
Cooling capacity = Considering a safety factor of 20%,
14.0 [kW] x 1.2 =
m x C x (T
0
– T
t
)
t
ρ
x V x C x T
t
1 x 250 x 4.186 x 10
3
x 12
900
16.8 [kW]
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 the r mo-chille r. The heating capacity depends on the circulating
fluid tempe rature. Consider the radiation r ate and heat capacity of the user’s equipment and che ck bef orehand if the required heating capacity is pr ovided.
2. Pump capacity
<Cir culating fluid fl ow rate>
Circulating flui d fl ow rate varies depending on t h e circulating fl uid dis ch arge pressure. Consider t he installation h ei gh t difference
between the the r mo-chiller and the user ’ s equipment, and the piping resistance such as circulating fluid pipings, or piping size, or
piping curv es in the machin e. Che ck bef orehand if the required fl o w is achi ev ed, using the pump capacity cu rves.
<Cir culating fluid dis charge pressure>
Circulating fluid discharge pressure has the possibility to increase up to the maxi m um pressure in the pump capacity cu rves.
Che ck bef orehand if the circulating fluid pipings or circulating fluid circuit of the user’ s equipment are fully durab le against this pressur e.
Circulating Fluid Typical Physical Property Values
1. This catalog uses the following values f or density and specific heat in calculating the required cooling capacit y.
Density
ρ
: 1 [kg/L] (or, using conventional units, w eight volume ratio = 1 [kgf/L] )
Specific heat C: 4.19 x 10 3 [J/(kg·K)] (or, using conventional units, 1 x 10 3 [cal/(kgf·
°
C)])
2. Values f or density and specific heat change slightly according to temperature shown below. Use this as a reference.
Water
P h ysical property
value
Temperature
Density
ρ
[kg/L]
Specific heat C
[J/(kg·K)]
Conventional units
Weight volume ratio [kgf/L] Speci fi c heat C [cal/(kgf·
°
C)]
5
°
C 1.00 4.2 x 10 3 1.00 1 x 10 3
10
°
C 1.00 4.19 x 10 3 1.00 1 x 10 3
15
°
C 1.00 4.19 x 10 3 1.00 1 x 10 3
20
°
C 1.00 4.18 x 10 3 1.00 1 x 10 3
25
°
C 1.00 4.18 x 10 3 1.00 1 x 10 3
30
°
C 1.00 4.18 x 10 3 1.00 1 x 10 3
35
°
C 0.99 4.18 x 10 3 0.99 1 x 10 3
40
°
C 0.99 4.18 x 10 3 0.99 1 x 10 3
Example of conventional units (Reference)
Heat quantity by cooled substance (per unit time) Q : Unkno wn [cal/h]
→
[W]
Cooled substance : Water
Cooled substance w eight m : (=
ρ
x V) [kgf]
Cooled substance w eight volume ratio : 1 [kgf/L]
Cooled substance total volume V : 250 [L]
Cooled substance specific heat C : 1.0 x 10 3 [cal/(kgf·
°
C)]
Cooled substance temper ature when cooling begins T
0
: 32 [
°
C]
Cooled substance temper ature after t hour T
t
: 20 [
°
C]
Cooling temperature difference T : 12 [
°
C] (= T
0
– T
t
)
Cooling time t : 15 [min]
Conversion factor: hours to mi nutes : 60 [min/h]
Conversion factor: kcal/h to kW : 860 [(cal/h)/W]
Q = =
=
≈
13953 [W] = 14.0 [kW]
Cooling capacity = Considering a safety factor of 20%,
14.0 [kW] x 1.2 =
m x C x (T
0
– T
t
)
t x 860
x V x 60 x C x T
t x 860
1 x 250 x 60 x 1.0 x 10 3 x 12
15 x 860
16.8 [kW]
∗
This is the calculated value b y changing the fluid tempe rature only.
Thu s, it var ies substantially depending on the w ater bath or piping shap e.
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The r mo-chiller
Water bath
V
After 15 minutes, cool 32
°
C down to 20
°
C.
20
°
C
Q x t: Heat capacity [kJ]
21