This article explained basic calculations for Plate Type Heat exchange design like hot fluid and cold fluid temperatures, heat transfer coefficient, heat transfer area calculation .. etc
Plate Heat Exchanger Heat Transfer Area Calculation | PHE Design Calculation
Basic concepts of Plate Type Heat Exchanger : (Please go through the below link)
Plate Heat Exchanger theory, structure and functional description, working and its application in Sugar Industry Process
Fundamental criteria for Plate and Frame Heat Exchanger design calculation
In the design of PHE mainly required two types of parameters –
-
- a) Process parameter
- b) Geometrical data
Process parameters: In a heat exchanger mainly done heat is exchanged from hot fluid to cold fluid
Hot fluid parameters
-
- Flow rate
- Inlet temperature
- Outlet temperature
- Density
- Thermal conductivity
- Specific heat
- Fouling factor
Cold fluid parameters
-
- Flow rate
- Inlet temperature
- Outlet temperature
- Density
- Thermal conductivity
- Specific heat
- Fouling factor
Geometrical data
-
- Length of plate
- Width of plate
- Corrugation angle
- Plate thickness
- Plate enhancement factor
- Amplitude of corrugation
- Flow configuration
The Overall heat transfer coefficient (OHTC) is a significate factor in the design of plate type heat exchange design
OHTC units – Kcal / hr/m2/ °C or Kw/m2/ °C,
It is mainly depends upon the following parameters
-
- a) Cold fluid film resistance
- b) Hot fluid film resistance
- c) Plate resistance – According to MOC (material of construction) of the plate
- d) Resistance of scale. ( fouling factor)
- e) Velocity of hot and cold fluid inside the heaters
For more information to calculating heat transfer coefficient please go through the link below.
- Heat Transfer Coefficient of Liquid -Liquid Tubular Heater Calculation
- Fundamental Concepts of Overall Heat Transfer Coefficient
Example for finding cold fluid outlet temperature
| S.No | Description | Formula | UOM | Values |
| A | Hot Side (Hot water) | |||
| 1 | Mass flow rate | Qh | Kg/hr | 120000 |
| 2 | Specific Heat | Cw | kcal/kg/°C | 1 |
| 3 | Inlet temperature | Ti | °C | 75 |
| 4 | Outlet temperature | To | °C | 50 |
| 5 | Heat Exchanged | H = Qh x Cw x (Ti – To) | Kcal/hr | 3000000 |
| B | Cold Side (Cane Juice) | |||
| 1 | Mass flow rate | Qc | Kg/hr | 160000 |
| 2 | Specific Heat | Cp | kcal/kg/°C | 0.93 |
| 3 | Inlet temperature | ti | °C | 35 |
| 4 | Outlet temperature | to = ti + [H /(Qc x Cp)] | °C | 55 |
Example for estimating vapour flow rate requirement to achieve the required outlet temperature of the cold fluid.
| S.No | Description | Formula | UOM | Values |
| A | Cold Side (Cane Juice) | |||
| 1 | Mass flow rate | Qc | Kg/hr | 270000 |
| 2 | Specific Heat | Cp | kcal/kg/°C | 0.95 |
| 3 | Inlet temperature | ti | °C | 95 |
| 4 | Outlet temperature required | to |
°C | 110 |
| 5 |
Heat Exchanged | H = Qh x Cw x (to – ti) | kcal/hr | 3847500 |
| B | Hot Side (Saturated Vapour) | |||
| 1 | Temperature of vapour | Tv | °C | 112 |
| 2 | Latent Heat of vapour | λ (As per steam table) | kcal/kg/°C | 531 |
| 3 | Vapour flow rate | Qh = H / λ (Not considered sensible heat of condensate) | Kg/hr | 7243 |
Online Steam Table for Saturated Steam
Example for Plate Type Heat Exchanger Heating Surface Calculation
| S.No | Description | Formula | UOM | Values |
| A | Hot Side (Hot water) | |||
| 1 | Mass flow rate | Qh | Kg/hr | 120000 |
| 2 | Specific Heat | Cw | kcal/kg/°C | 1 |
| 3 | Inlet temperature | Ti | °C | 75 |
| 4 | Outlet temperature | To | °C | 55 |
| 5 | Heat Exchanged | Qh x Cw x (Ti – To) | kcal/hr | 2400000 |
| B | Cold Side (Cane Juice) | |||
| 1 | Mass flow rate | Qc | Kg/hr | 160000 |
| 2 | Specific Heat | Cp | kcal/kg/°C | 0.93 |
| 3 | Inlet temperature | ti | °C | 35 |
| 4 | Outlet temperature | to | °C | 51 |
| 5 | Heat Exchanged | Qc x Cp x (to – ti) | Kcal/hr | 2400000 |
| C | Logarithmic Mean Temperature Difference ∆T m (LMTD) | |||
| 1 | ∆T | to – ti | °C | 16.1 |
| 2 | ∆Ti | ti-To | °C | 23.9 |
| 3 | ∆To | to – Ti | °C | 20.0 |
| 4 | ∆T m | ∆Ti – ∆To / [Ln(∆Ti / ∆To)] | 21.9 | |
| D | Heat transfer Coefficient | Kcal/hr/m2/oC | 1800 | |
| E | Heating surface | Qh x Cp x ∆T = K x S x ∆Tm | m2 | 60.9 |
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