Heat Transfer calculation for Tank and piping system

In summary, the conversation discusses a heat transfer equation for a liquid tank and piping system. The tank contains 900 kg of water, heated by a 1kW heater, and the piping system circulates 30 liters/minute of water at 36°C back into the tank. The goal is to calculate the time it will take to heat the tank to 53°C. The conversation also includes calculations for the heat loss in the piping system.
  • #1
emericas2015
4
0
Having difficulty remembering how to model a simple heat transfer equation for a liquid tank/piping system and wondering if anyone can provide some quick help.

I have a 1000L tank of water that is heated by a 1kW heater (target temp of 43°C). The piping system (outside of the tank), holds 100L of water at any given time and circulates the fluid from and back into the tank at 30 liters/minute. The temperature of the liquid on return is 36°C (so a delta T of about 7°C attributed to heat loss of the piping).

So basically, I have 900 kg reservoir of water at 43°C that is being heated by a 1kW heater, while also being subject to cooling by a return line of the fluid at a mass flow rate of 30 kg/min at a temperature of 36°C. Assuming the Qout of the tank is zero as the tank is insulated and sealed.

Looking for help to get a heat transfer model on this system. Looking to calculate the time it will take to heat and run the tank reservoir at a temperature of 53° C (so, 10°C above the current temp)Thanks for all and any help!

Ethan
 
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  • #2
OK. You start out by assuming that the water in the tank is well-mixed so that its temperature is uniform. If T is the temperature in the tank, what is the temperature of the exit stream?
 
  • #3
The exit stream temperature is the same temperature as inside the tank. Also assuming that the exit stream vs return stream delta T is constant (so, 7 degrees cooler upon return).
 
  • #4
OK. You're going to do a transient heat balance on the tank. The internal energy in the tank is U=MC(T-T0), where M is the mass of water in the tank, C is the heat capacity, and T0 is some arbitrary reference temperature. How is M related to the volume and the density of the water? Let Q represent the heating rate of the heater. Let w represent the rate that water exits the tank and enters the tank. Let's see if you can write down a transient heat balance on the tank.

Chet
 
  • #5
Ahhhh, thank you so much. Finally jogged my memory and got it figured out!
 
  • #6
Just for info.. I made the loss in the pipe work far more than 1kW...

P (in Watts) = mCΔT

where
m is the mass flow rate in kg/S (30L/min = 0.5Kg/S)
C = specific heat capacity (4181J/Kg/C)
ΔT = 7 degrees

P = 0.5 * 4181 * 7 = 14KW

So tank won't be heating up.
 

1. What is heat transfer and why is it important in tank and piping systems?

Heat transfer is the exchange of thermal energy between two or more objects. In tank and piping systems, heat transfer is important because it affects the temperature of the system's contents and can impact the efficiency and safety of the system.

2. How is heat transfer calculated for tank and piping systems?

The most common method for calculating heat transfer in tank and piping systems is through the use of the heat transfer coefficient. This coefficient takes into account factors such as the material properties of the tank or pipe, the flow rate of the fluid, and the temperature difference between the fluid and the surrounding environment.

3. What are the different modes of heat transfer in tank and piping systems?

The three main modes of heat transfer in tank and piping systems are conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between objects, convection is the transfer of heat through the movement of fluids, and radiation is the transfer of heat through electromagnetic waves.

4. How does insulation impact heat transfer in tank and piping systems?

Insulation can greatly impact heat transfer in tank and piping systems as it acts as a barrier to slow down the rate of heat transfer. By reducing the amount of heat lost to the surrounding environment, insulation can improve the efficiency and energy consumption of the system.

5. What are some factors that can affect heat transfer in tank and piping systems?

Some factors that can affect heat transfer in tank and piping systems include the material and thickness of the tank or pipe, the flow rate and temperature of the fluid, the type and amount of insulation, and the surrounding environment (e.g. air temperature, wind speed, etc.). Other factors such as the design and placement of the tank or piping system can also impact heat transfer.

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