Plate heat exchanger NTU method effectiveness

In summary, the individual is seeking assistance with the evaluation of a pilot plant heat exchanger and its potential as a replacement for larger installations. The NTU method was used to calculate the effectiveness of the heat exchanger, but the result was consistently 1. The exchanger is a counter flow plate heat exchanger and has the following specifications: steam pressure in at 120 kPa, steam temperature in at 400 C, other fluid temperature in at 110 C, steam flow in at 0.278 kg/s, other fluid flow in at 1.806 kg/s, heat transfer coefficient at 2.5 [kw/(m^2 C)], contact area at 40 m^2, steam heat capacity at 2
  • #1
ram33
Hi All

I need to do an evaluation of a pilot plant heat exchanger that we have installed and see if it would be better suited than our current bigger installations. I was trying to calculate the effectiveness of the heat exchanger but I keep on getting 1 with the NTU method. Below is the information that I have so any suggestions on how to do this would be greatly appreciated. It is a counter flow plate heat exchanger.

Steam pressure in = 120 kPa
Steam Temperature in = 400 C
Other fluid temperature in = 110 C
Steam flow in = 0.278 kg/s
Other fluid flow in = 1.806 kg/s
Heat Transfer Coefficient = 2.5 [kw/(m^2 C)] (Calculated when the trail was done).
Contact Area = 40 m^2
Steam heat capacity = 2.07 kJ/kg K
Other fluid heat capacity = 3.91 kJ/kg K

The steam comes out as condensate.

I would appreciate your help.
 
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  • #2
ram33 said:
Hi All

I need to do an evaluation of a pilot plant heat exchanger that we have installed and see if it would be better suited than our current bigger installations. I was trying to calculate the effectiveness of the heat exchanger but I keep on getting 1 with the NTU method. Below is the information that I have so any suggestions on how to do this would be greatly appreciated. It is a counter flow plate heat exchanger.

Steam pressure in = 120 kPa
Steam Temperature in = 400 C
Other fluid temperature in = 110 C
Steam flow in = 0.278 kg/s
Other fluid flow in = 1.806 kg/s
Heat Transfer Coefficient = 2.5 [kw/(m^2 C)] (Calculated when the trail was done).
Contact Area = 40 m^2
Steam heat capacity = 2.07 kJ/kg K
Other fluid heat capacity = 3.91 kJ/kg K

The steam comes out as condensate.

I would appreciate your help.
Please show us the details of your analysis.
 

Related to Plate heat exchanger NTU method effectiveness

1. What is the Plate Heat Exchanger NTU method?

The Plate Heat Exchanger NTU (Number of Transfer Units) method is a calculation used to determine the effectiveness of a plate heat exchanger. It takes into account the heat transfer area, fluid flow rates, and heat capacities to determine the efficiency of the heat exchanger.

2. How does the NTU method calculate effectiveness?

The NTU method uses the ratio of the actual heat transfer rate to the maximum possible heat transfer rate to determine the effectiveness. This ratio is then used to calculate the number of transfer units (NTU) for the heat exchanger. The effectiveness is then calculated using the NTU and the heat capacity rates of the two fluids.

3. What factors affect the effectiveness of a plate heat exchanger?

The effectiveness of a plate heat exchanger is affected by the heat transfer area, the fluid flow rates, the heat capacity rates of the fluids, and the temperature difference between the two fluids. Other factors such as fouling and corrosion can also affect the effectiveness over time.

4. How is the NTU method used in the design of plate heat exchangers?

The NTU method is an important tool in the design of plate heat exchangers as it helps engineers determine the optimal heat exchanger size and configuration. By using the NTU method, engineers can ensure that the heat exchanger will effectively transfer heat between the two fluids without wasting energy.

5. What are the limitations of the Plate Heat Exchanger NTU method?

While the NTU method is a widely used and accepted method for calculating the effectiveness of plate heat exchangers, it does have its limitations. It assumes that the heat exchanger operates under steady-state conditions, and it does not account for factors such as fouling and corrosion. Additionally, the NTU method is not suitable for heat exchangers with multiple fluid streams or non-uniform fluid flow.

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