Kim S_Seawater Heating and Cooling in Busan, Korea

Analysis of Proper Depth
for Gaining Seawater Heat
for Heating and Cooling
in Busan, Korea
• Samuel Kim (Dongeui University)
• Ki-Chang Chang (Korea Institute of Energy Research)

1. Introduction
• Use of heat from seawater could be different from the weather conditions
of a coastal city and seawater temperatures near the city.
• It is impossible to get deep sea water for Busan area, since the
maximum sea water depth around Busan is about 150m.
• It will be a good option to use surface layer water with Heat Pump
system for using seawater cooling/heating in Busan.
• The study investigates the proper depth for seawater heat gain of Busan
area in Korea : Sampling points are 0, 10, 20, 30, 50m from the surface
of the Sea.
• Proper seawater intake depth for heating and cooling in Busan is
suggested, through investigating the temperature of seawater according
to the depth

2. Examples of seawater heat source facilities
Korean Cases
KIOST
* Use of Deep Seawater for Air
conditioning of the building.
* A small size pilot project (60RT)
* About 86% of cooling energy is
saved.
Korea Maritime University
* 75RT Size Heating and Cooling
System using Plate-type Heat
Exchanger.
* Flow Rate : 60m 3 /h ,
COP for Cooling : 7
COP for Heating : 6.8
* About 70% of electricity energy
is saved.

3. Analysis of seawater temperature
30.00
25.00
Temperature (°C)
20.00
15.00
10.00
5.00
Point 1
207 Area
0.00
FEB APR JUN AUG OCT DEC
0m 10m 20m 30m 50m
Point 1 of 207 Area
207 Area Point 1 Point 2 Point 3
Distance 2km 14km 22km
Depth 84m 103m 115m
• Temperature Analysis for Sea
Water at Point 1 of 207 area
between 2000 and 2011.
• The temperature of surface water
fluctuates according to the season,
while that of deep sea water is
constant.

3. Analysis of seawater temperature
Point 1 of 207 Area
30
30
Temperature (°C)
25
20
15
10
5
Temperature (°C)
25
20
15
10
5
depth
0m
0
FEB APR JUN AUG OCT DEC
depth
30m
0
FEB APR JUN AUG OCT DEC
Temperature (°C)
Temperature (°C)
30
25
20
15
10
5
0
depth
10m
30
25
20
15
10
depth
20m
5
0
FEB APR JUN AUG OCT DEC
FEB APR JUN AUG OCT DEC
2011 2010 2009 2008 2007 2006
2005 2004 2003 2002 2001 2000
Temperature (°C)
depth
50m
30
25
20
15
10
5
0
FEB APR JUN AUG OCT DEC
• Seawater temperature does not
change significantly according to
the depth in winter, while the
temperature is quite different
according to the depth in summer.
Comparison Parts

4. Energy potential of seawater heat source
• Q is an energy potential of seawater heat source
Q = ρ * Cp * W * ∆t
ρ : density of seawater(1,025kg/m 3 ) Cp : Specific heat (0.942kcal/kgK)
W : flow (10 4 m 3 /month/m) ∆t : temperature difference
∆t FEB APR JUN AUG OCT DEC
0m 4.84 1.28 4.33 10.07 0.8 6.75
10m 4.71 1.45 5.36 10.24 1.17 6.67
20m 4.34 1.94 7.96 14.66 8.72 6.24
Gcal/month
250000
200000
150000
100000
50000
0
2 4 6 8 10 12
Month
Energy potential is the
biggest in summer
depending on the
temperature difference.
When the water level is
deeper, the energy
potential becomes
bigger.
0m 10m 20m

5. Analysis of cost for seawater intake pipes
• If the heat pump with 150A HDPE pipes is operated, the cost per pipe
length(m) is 27,100 Won.
• The distance form the coast of 0 m depth below sea level is 0.095 km, that
of 10 m depth is 0.476 km, and that of 20 m is 1.19 km
• The cost of pipes for the intake depth of 0 m is 2.6 million Won, that of 10 m
is 130 million won, and that of 20 m is 320 million Won.
Won
50,000,000
45,000,000
40,000,000
35,000,000
30,000,000
25,000,000
20,000,000
15,000,000
10,000,000
5,000,000
0
0m 10m 20m
Depth
Energy potential Cost
35,000,000
30,000,000
25,000,000
20,000,000
15,000,000
10,000,000
5,000,000
0
Gcal/day∙°C
US$ 1 ≒ Korean Won 1,100
• The energy potential
between 0m and 10m
depth is similar.
• The cost of intake pipes
varies by the distance
from the coast and
seawater depth level.

6. Conclusion
• The temperature difference according to the depth of seawater is
relatively big during August, while it is almost the same from October to
April.
• The installing cost for intake pipes for 20m depth is about 3 times higher
than that for 10m.
• Although the COP of the system using deeper seawater is higher than
that using shallower seawater, the initial cost of the system using deeper
seawater is much higher that that using shallower seawater.
• Use of seawater from 10m depth is more economical than that from 20m.