1. An Analytical Study of Cooling Pond System for
Coreless Induction Furnace
Presented by
THANT ZIN WIN
Department of Mechanical Engineering
Technological University (Kyaukse)
Mandalay Division, Myanmar
MG THANT ZIN WIN

2. Presentation Outlines
Introduction
Operating Principle of Coreless Induction Furnace
Important Role of Water Cooling
Types of Water Cooling System
Layout Description
Design Parameters of Cooling Pond
Pond Design Model Consideration
Equilibrium Temperature and Surface Heat Flux
Pond Design Calculation
Case Study
Cooling Pond Performance
Conclusion
Further Suggestions
MG THANT ZIN WIN

3. Introduction Electric Induction Furnace Core Type Coreless Type
Fig 1 – Core and Coreless Type of Induction Furnace
MG THANT ZIN WIN

4. Operating Principle of Coreless Induction Furnace
Electromagnetic induction
Connect to a source of AC
Create thermal energy
Melt the charge
Stirring action caused
by molten metal
Fig 2 - Simplified Cross Section of Coreless Induction Furnace
MG THANT ZIN WIN

5. Important Role of Water Cooling
Water is vital to be success.
Need high water quality.
Flow velocity of all water circuit should be monitored.
Fig 3 - A Sample Induction Coil with Cooling Water
Cooling water supply temperature should not be below 25°C.
Upper limit of leaving the coil should be no more than 70°C.
If too cold water is allowed, condensation may be formed.
Fig 4 - Sample of the Damaging Induction Coil
MG THANT ZIN WIN

6. Types of Water Cooling System
The types of water cooling system are as follow:
Cooling Pond System
Spray Pond System
Evaporative Cooling Tower – Open-circuit System
Fan-radiator Closed-circuit System
Water/water Heat Exchanger Dual System
Dual System with Closed-circuit Cooling Tower
MG THANT ZIN WIN

7. Cooling Pond System Process Description Large ground area
Hot water inlet
Cool water outlet
Water surface
Pond
Large ground area
Small investment
Fig 5 – Sketch of Typical Cooling Pond System
Process Description
24.33 ft3/min
Cool water inlet
Pumps
Hot water outlet
Control panel
Capacitor bank
Furnace 2
Furnace 1
Cooling pond
(8,000 ft3)
Fig 6 – Schematic Diagram of
Cooling Pond Model
MG THANT ZIN WIN

8. Layout Description of 0.16 ton Coreless Induction Furnace
Suction Pipeline
Discharge Pipeline
Cooling Pond
Furnace No. 1
Furnace No. 2
Control Panel
Capacitor Bank
Pump
Fig 7 - Functional Layout of 0.16 ton Coreless Induction Furnace
MG THANT ZIN WIN

9. Design Parameters of Cooling Pond
The hot water or inlet temperature into the pond
The cool water or outlet temperature from the pond
The operating time occupied in melting
The solar heat flux or solar energy identified as the main heating mechanisms
The pond volume and size corresponding to the equilibrium temperature
MG THANT ZIN WIN

10. Pond Design Model ConsiderationTa
Interchange with Atmosphere
Cooling Pond Td H
V = volume
T = temperature
A = area W
Q, T
Ti, R Ts
V, T TE
Q = Outflow rate
R = inflow rate Tb
Induction Furnaces
Fig 8 - Illustrative Diagram of Cooling Pond Model
MG THANT ZIN WIN

11. Equilibrium Temperature and Surface Heat Flux
Wind
speed
sc s a
ar
br e c
Ground
Subsurface
conduction
Hot water
inlet
Cool water
outlet
sr
R, To
Q, Ti
Tsw W2 Ta Td TE
sn
an Tb T
Sun
Fig 9 – Heat Transfer Mechanisms in Cooling Pond

12. Pond Design Calculation
Known Data
Relative humidity, RH = 62%
Ambient air, Ta = 88ºF
Dew point, Td = 72ºF
Hot water, Ti = 91.4ºF
Cold water, To = 82.4ºF
Latitude of Yangon, = N
Wind speed, W = 4 mph
Flow rate, Q = ft3/min
Assumptions
Steady-state (Completely mixed Pond)
Inflow rate is equal to outflow rate
Ts = T (Completely well-mixed pond)
No seepage into or from groundwater
Neglect heat conduction between the surrounding soil
Heat exchange occurs near the pond surface only
Volume, V = constant
Density, ρ = constant
At time t = 0, T = 28ºC
Pond volume
Pond surface area
where,
kr = water retention rate
kT = thermal rate
MG THANT ZIN WIN

13. Case Study Data for the Example Parameter Specified Value Capacity
0.16 ton
Current frequency
1,000 Hz
Metal overheating temperature
2.912°F
Consumed power
16 kW
Dry bulb temperature
88°F
Relative humidity
62%
Wind speed
4 mph
Entering water temperature
82.4°F
Leaving water temperature
91.4°F
Latitude of Yangon
16.45 N

14. Cooling Pond Performance
The results corroborate the fact that the most important variable on
cooling pond performance is pond surface area itself, but not is volume.

15. Conclusion
Cooling system is the important part of coreless induction furnace.
Cooling ponds are one of the economically competitive alternatives for removing of heat from induction furnaces.
The most important influence factor on the cooling pond configurations is pond surface area.
MG THANT ZIN WIN

16. Further Suggestions Extending the baffles in the pond.
Highly baffled pond, longitudinal baffles, rectangular discharge
Highly baffled pond, lateral baffles, rectangular discharge
Using the heat exchangers.

17. MG THANT ZIN WIN

18. Fig - Sample Spray Pond System
Use a number of nozzles
Depend on relative humidity
MG THANT ZIN WIN

19. Fan-radiator Closed-circuit System
Fig - Fan-radiator (closed-circuit) System
Completely enclosed
Loss of water is slight
MG THANT ZIN WIN

20. Water/water Heat Exchanger Dual System
Fig - Dual System with Water/water Heat Exchanger
More compact
Easier to clean and maintain
MG THANT ZIN WIN

21. Dual System with Closed-circuit Cooling Tower
Fig - Dual System with Closed-circuit Cooling Tower
Slightly more expensive
Lower Piping and pumping costs
MG THANT ZIN WIN

22. Types of Cooling Tower Fig - Mechanical Draft Cooling Towers
Fig - Natural Draft Cooling Towers

23. Cooling Pond Area and Volume Calculation
By using the following equations,
The type of pond is shallow
Declination angle,
The hour angle,
Maximum possible sunshine duration,
The extraterrestrial solar radiation ,
Ref: Magal, B. S. (1999), Solar Power Engineering, Fourth reprint, TATA McGraw Hill Publishing Company Limited, Bombay.
MG THANT ZIN WIN

24. Clear sky solar radiation,
Equilibrium temperature by using the iterative method,
The net heat flux,
MG THANT ZIN WIN

25. The net heat exchange coefficient,
Normalized intake temperature,
Pond cooling capacity,
Required cooling pond area,
MG THANT ZIN WIN

26. By implementing to unit depth, the volume of cooling pond is
Approximately, the volume
is used in the construction.
From the above volume and area, the relationship between the temperature and operating time is obtained as follows:
Where, kr = water retention rate
kT = thermal rate
MG THANT ZIN WIN

27. Solar Heat Flux Sun Cloud Fig – Components of Surface Heat Transfer
sc
br e c
Cloud
sr a
ar s
Water surface
sn
an
Fig – Components of Surface Heat Transfer
where, n = the net heat flux into the water surface
sn = the net solar (short-wave) radiation into the water surface
an = the net atmospheric (long-wave) radiation from the water surface
br = the back (long-wave) radiation from the water surface
e = the evaporative heat flux from the water surface
c = the conductive heat flux from the water surface
s = the solar radiation at water surface
sr = the reflected solar radiation
a = the atmospheric (long-wave) radiation
ar = the reflected atmospheric radiation
MG THANT ZIN WIN