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Design Calculation of Heat Exchanger

What is Design Calculation of Heat Exchanger ?

Design calculations for a heat exchanger are vital for optimizing thermal overall performance and performance. The procedure starts by figuring out the heat obligation (Q), that is the desired heat transfer based totally at the temperature alternate of the fluids. This is calculated by the usage of the formula Q=m˙×Cp×(Tin−Tout) where m˙is the mass flow rate and Cp​ is the specific heat capacity.

Next, the correct heat exchanger kind (e.g., shell-and-tube, plate) is selected primarily based on the application. The usual heat transfer coefficient (U) is decided by evaluating thermal conductivities and the fouling thing. The log implies temperature distinction (LMTD) is calculated to evaluate the temperature gradient across the exchanger.

Using the equation Q = U × A × LMTD, the specified surface area (A) is derived. Finally, pressure drop calculations ensure system performance and material selection is based totally on thermal properties and corrosion resistance.

Design Calculation of Heat Exchanger


Find Shell and Tube Heat Exchanger Sizing Calculator Online

Users commonly enter parameters such as fluid properties (temperature, flow rate, precise warmth), preferred heat transfer responsibility, and typical heat transfer coefficient.

The calculator then computes key metrics, which include the required surface area, tube length, and diameter. Additionally, it can check pressure drop and suggest the most excellent configurations. By providing a quick and correct sizing answer, those calculators assist in streamlining the design method and enhance performance in thermal management programs.

Shell and Tube Heat Exchanger Sizing Calculator

Table of Contents


heat-exchanger

What is the Working Principle of Heat Exchanger?

The working principle of a heat exchanger includes the transfer of thermal power between fluids without mixing. Hot fluid enters one side, whilst cold fluid enters the alternative aspect. As the fluids glide past every different, heat transfers from the hor fluid to the cold fluid via the walls of the heat exchanger, inflicting the hot fluid to quiet down and the cold fluid to heat up.

Various flow arrangements, consisting of counterflow or parallel flow, affect the performance of heat transfer. This manner is vital in applications like HVAC structures, refrigeration, and business processes, enhancing strength efficiency and performance.

Working Principle of Heat Exchanger

Principle Explanation
Function Without Mixing, Transfers Heat Between Two Fluids.
Flow Arrangement Parallel Flow, Counterflow, Crossflow.
Heat Transfer Depend on the Temperature Variation Between Fluids.
Heat Transfer Area Wider Area Improves Heat Exchange and Efficiency.
Thermal Conductivity High Conductivity Materials Perform Better.
Fluid Types Liquids or Gases
Effectiveness Described as the Ratio of the Maximal Allowable Transfer to the Actual Heat Transfer.
Design Considerations Contain Fouling, Pressure Drop, and Maintenance Requirement

 

Types Of Heat Exchanger

Shell and Tube Heat Exchanger

Shell and Tube Heat Exchanger

Plate Heat Exchanger

Plate Heat Exchanger

Air Cooled Heat Exchanger

Air Cooled Heat Exchanger

Fin Tube Heat Exchanger

Fin Tube Heat Exchanger

Spiral Heat Exchanger

Spiral Heat Exchanger

Tubular Heat Exchanger

Tubular Heat Exchanger

Plate Heat Exchanger Vs Shell and Tube

Value Plate Heat Exchanger Shell and Tube Heat Exchanger
Design Made Up of Several Thin Plates. Has a Shell That Contains a Number of Tubes.
Efficiency Because of Turbulence, Usually More Effective in Transferring Heat. Excellent Efficiency, but Subject to Flow Configuration.
Heat Transfer Area Higher Ratio of Surface Area to Volume. Lower the Ratio of Surface Area to Volume.
Maintenance Simpler to Maintain More Complicated
Fouling Resistance Easier to Clean but More Sensitive to Fouling. Can Be Built to Reduce Fouling, but May Require Additional Upkeep.
Size and Weight Lighter and More Compact Heavier and Bulkier
Fluid Compatibility Restricted to Lower Temperatures and Pressures Able to Tolerate High Temperatures and Pressures
Cost Lower Starting Expenses Greater Beginning Costs
Application Pharmaceuticals, Food Processing, and HVAC Systems. Oil Refineries, Power Plants, Chemical Processing.

Check Plate Heat Exchanger Weight Calculator Formula With Example Here

Plate heat exchanger weight calculation includes many factors, like plate dimensions, number of plates, and type of material used. The entire weight of a plate heat exchanger can be approximately calculated using below formula

Heat Exchanger Weight Calculator Formula

Weight (W) = Volume (V) × Density (ρ)

Where:

  • V: Volume is in cubic meters (m³).
  • W: Weight is in kilograms (kg).
  • ρ: Density is the density of the material (kg/m³).

Plate Baffles Vs Rod Baffle

Plate Baffles Vs Rod Baffle

Both are baffle design used in shell and tube heat exchangers to improve heat transfer and fluid flow. Plate baffles are flat plates and rod baffles include vertical rods. It offer excellent fluid cicrculation

Value Plate Baffles Rod Baffles
Design Flat Plates Offer Flow Channels. Cylindrical Rods Are Located Within the Shell.
Applications Pharmaceuticals, Food Processing Oil Refining , Chemical Industry
Heat Transfer Efficiency Generally Higher Due to Larger Surface Area. Effective, but Somewhat Less Efficient Than Plate Baffles.
Flow Arrangement Encourages Directed Flow and Increases Turbulence. Creates Segmented Flow Pathways to Improve Heat Transfer.
Maintenance Cleaning and Inspecting is Easier. Rod Placement Makes Cleaning More Difficult.
Cost Lower Higher
Pressure Drop Flow Limitation Might Create a Higher Pressure Drop. Pressure Drop is Lower Compared to Plate Baffles.
Installation Assembly is Simplified by Using Fewer Parts. Assembly and Alignment Are More Challenging.

Calculate Weight Using Heat Exchanger Weight Calculator in Kg Online

To find the heat exchanger weight in kg, first need to calculate the weight of a single plate or tube. Then multiply the single component weight by a number of components to find the final weight. Refer to the formula and calculator

Heat Exchanger Weight Calculator in Kg

Approximate weights are given. Different wall thicknesses are found in tube mills.


OD (Outside Diameter)


Wall Thickness



-774.5 lbs Per Foot

Fixed Tube Sheet Vs U Tube Bundles

Fixed Tube Sheet Vs U Tube Bundles

Both are tube bundle types. Fixed tube sheets have tubes that are attached at both ends to tube sheets. It is ideal for lower-temperature uses. In u tube bundle tubes are bent in u shape. This design is used in high-temperature applications

Value Fixed Tube Sheet U-Tube Bundle
Design The Tubes Are Secured at Both Ends. Tubes Are Bent Into a U Form.
Thermal Expansion There is Limited Expansion Capability. Allows for Thermal Expansion.
Heat Transfer Efficiency High Efficiency Lower Than Fixed Tube Sheet
Maintenance Cleaning Requires Complete Disassembly. Simpler to Maintain Without Complete Disassembly.
Cost Lower Initial Cost. Higher Initial Cost
Applications High-pressure Applications. Perfect for a Variety of Loads and Temperature Cycles.
Pressure Drop Higher Pressure Drop. Lower Pressure Drop.
Fluid Compatibility Best for Fluids That Have Similar Characteristics. Handles Various Fluid Characteristics Effectively.
Understand Heat Exchanger Pressure Drop Calculation

Calculation of pressure drop across heat exchanger is important to confirm proper operation. For this calculation first need to find fluid viscosity and density as well as tube length and diameter

Heat Exchanger Pressure Drop Calculation

Formula for Pressure Drop Calculation

ΔP = f . L/Dh . Pv2/2

Where:

  • ΔP = Pressure drop (Pa)
  • f = Friction factor
  • L = flow path Length
  • D_h = Hydraulic diameter (m)
  • ρ = density of fluid (kg/m³)
  • v = velocity of fluid (m/s)

Gauge Pressure Of Shell and Tube Heat Exchanger

Unit Torr
(Torr) 		bar
(bar) 		Pascal
(Pa) 		atmosphere
(atm) 		pound per square inch (psi)
1 bar 750 106 dyn/cm2 100000 0.9867 14.5
1 Pa 0.0075006 0.00001 1 N/m² 0.000009867 0.000145
1 at 735.5 0.980665 98066 0.968 14.223
1 torr 1 mmHg 0.013332 133.322 0.0013158 0.0193
1 atm 760 1.01325 101325 1 atm 14.7
1 psi 51.72 0.068948 0.006894 0.068046 1 lbf/in²
Get Heat Balance Equation and Heat Load Calculation of Heat Exchanger Here

Heat balance equation for the heat exchanger is required to find energy transfer between two fluids and heat load calculation is needed to identify the required size and capacity to transfer heat between two fluids.

Heat Balance Equation for Heat Exchanger

Basic Equation is

Where:

  • Q out​= hot fluid lost heat (kW or J/s)
  • Q in​= cold fluid heat gained(kW or J/s)

Heat Transfer Coefficients in Heat Exchangers

Heat Exchangers Heat Transfer Coefficients
Type U Btu/(h.ft².°F) U W/(m².K)
Tubular, condensation 50 - 200 300 - 1200
  250 - 700 1500 - 4000
Spiral heat exchanger 150 - 700 900 - 3500
  125 - 500 700 - 2500
Tubular, heating or cooling 35 - 70 200 - 400
25 - 90 150 - 500
1 - 6 5 - 35
3 - 15 15 - 70
50 - 200 300 - 1200
25 - 200 150 - 1200
Plate heat exchanger 150 - 700 1000 - 4000
Air-cooled heat exchangers 10 - 30 60 - 180
70 - 95 400 - 550
100 - 130 600 - 750
5 - 10 30 - 60
125 - 150 700 - 850
35 - 80 200 - 450
65 - 90 350 - 500
Tubular, evaporation 100 - 300 600 - 1700
50 - 150 300 - 900
150 – 500 900 - 3000

Heat Exchanger Heat Load Calculation

Heat Load is calculated using below formula

Q = m ˙ . c p​ . ΔT

Where:

  • Q= Heat load (kW or J/s)
  • m˙= Fluid mass flow rate (kg/s)
  • c p = Fluid specific heat capacity (kJ/kg·K or J/kg·K)
  • ΔT= Fluid temperature change (K or °C)

Material Wise Heat Value for Heat Exchanger

Product Heat Capacity - Cp
(Btu/lb oF) (J/ g °C)
Ammonia, 104oF 1.16 4.86
Alcohol, ethyl 32oF (ethanol) 0.55 2.3
Dowtherm 0.37 1.55
Castor Oil 0.43 1.8
Fuel Oil max. 0.5 2.09
Freon R-12 saturated 0oF 0.217 0.91
Heptane 0.535 2.24
Gasoline 0.53 2.22
Kerosene 0.48 2.01
Light Oil, 60oF 0.43 1.8
Gold 0.0308 0.129
Light Oil, 300oF 0.54 2.3
Octane 0.51 2.15
Mercury 0.03 0.14
Oil, mineral 0.4 1.67
Petroleum 0.51 2.13
Olive oil 0.47 1.97
Propylene Glycol 0.60 2.5
Water, sea 36oF 0.94 3.93
Propane, 32oF 0.576 2.4
Sodium chloride 0.79 3.31
Toluene 0.41 1.72
Soya bean oil 0.47 1.97
Water, fresh 1 4.19

Heat Exchanger Tube Dimentional Arrangement

Tube Diameter Triangular Pitch Square Pitch
¾” (19 mm) 15/16” or 1” (24 or 25 mm) 1” (25 mm)
5/8” (16 mm) 25/32” (20 mm) 7/8” (22 mm) (Note = 1)
1 ¼” (32 mm) 1 9/16” (39 mm) 1 9/16” (39 mm)
1” (25 mm) 1 ¼” (32 mm) 1 ¼” (32 mm)
1 ½” (38 mm) 1 7/8” (47 mm) 1 7/8” (47 mm)

Triangular Pattern Vs Square Pattern Tubes

Triangular Pattern Vs Square Pattern Tubes

Tubes are arranged With closely in a triangle pattern. Manufacturing and cleaning this design is complex. in square patterns arrangement of tubes are in grid layout which are easy to maintain and cleaning

Value Triangular Pattern Tubes Square Pattern Tubes
Heat Transfer Efficiency Increased efficiency due to improved fluid mixing. Medium efficiency; more consistent flow.
Arrangement The tubes are placed in a triangle grid. Tubes are organized in a square grid.
Space Utilization A compact layout that maximizes surface area. Effective but less compact than triangular.
Fluid Flow Increases turbulent flow, which improves heat transfer. Offers laminar flow properties.
Pressure Drop pressure drop is lower. Tighter packing leads to a higher pressure drop.
Applications heat exchangers. standard industrial applications.
Maintenance Cleaning is more convenient. Can be more difficult to clean.
Cost higher because of complex design. lower starting cost.

Flat Plate Heat Exchanger Fouling Resistances Coefficients

  Cooling Tower Treated
Make-up 		  0.002   0.001   0.001   0.002
Untreated
Make-up 		0.004 0.003 0.003 0.005
River Water Minimum 0.002 0.001 0.002 0.003
Average 0.003 0.002 0.003 0.004
Muddy Water   0.0003 0.0002 0.0003 0.0004
Distilled Water   0.0005 0.0005 0.0005 0.0005
Sea Water   0.0001 0.0005 0.0005 0.0001

 

Fouling Resistances Coefficients Of Cooling Water (ft² h °F/Btu)
Hot Fluid Temperature Up to 240 °F 240 °F to 400 °F
  Water Temperature Up to 125 °F Over 125 °F
Velocity Up to 3 ft/s Over 3 ft/s Over 3 ft/s Up to 3 ft/s
City Water   0.001 0.001 0.002 0.003
Boiler Feed (Treated)   0.001 0.005 0.001 0.001
Boiler Blowdown   0.002 0.002 0.002 0.002
Condensate   0.0005 0.0005 0.0005 0.0005

 

Fouling Factors [m2K/W]:
Process Fluid Fouling Factors
    Liquids Vegetable Oils 0.00053
Organic heat transfer fluids 0.00018
Cooling Fluid 0.00018
LPG, LNG 0.00018
Caustics 0.00035
    Gas and Vapor Compressed air 0.00035
Steam 0.00009
Natural gas 0.00018
Hydrogen 0.00176
Organic solvent vapors 0.00018
          Products Heavy gas oil 0.00053
Kerosene 0.00018
Gasoline 0.00018
Light gas oil 0.00035
Light cycle oil 0.00035
Heavy fuel oils 0.00088
Light coke gas oil 0.00053
Heavy cycle oil 0.00053
Liquid products 0.00018
Heavy coke gas oil 0.00070
Reboiler streams 0.00053
Absorption oils 0.00035
Solvent 0.00018
Lube oil processing streams 0.00053
   

NTU vs LMTD

Selection between LMTD (Log Mean Temperature Difference) and NTU (Number of Transfer Units) for heat exchanger based on application. LMTD is suitable for simpler designs and NTU method is for handling complex design

Value NTU (Number of Transfer Units) LMTD (Log Mean Temperature Difference)
Definition Measures a heat exchanger's efficiency. Shows the average temperature difference.
Use Suitable for all heat exchanger types. Ideal for counterflow and parallel flow configurations.
Method Of Calculation Based on performance and capacity. Temperatures at intake and outlet are used to calculate this.
Effectiveness Directly related to exchanger efficacy. Assumes a constant temperature gradient.
Complexity Of Formula Calculations are more difficult. A simpler temperature difference formula.
Heat Exchanger Type air and liquid exchangers. liquid-to-liquid exchangers.
Use Case Useful when flow rates are unknown. When the temperature is known, this is useful.

Plate and Frame Heat Exchanger Physical Properties

Property Units Liquids Water Air Steam Vapors
    Density kg/m³ 700 - 1500 1000 1.29@STP (1.0
bar, 0°C)		    
lb/ft³ 43.6 - 94.4 62.29 0.08@STP
(14.7 psia, 60°F)		    
Prandtl Nbr   10 - 1000 1 -15 0.7 1.0 0.7 – 0.8
Heat Capacity KJ/kg °C 1.0 - 2.5 4.2 1.0 2.0 2.0 - 4.0
Btu/lb °F 0.239 - 0.598 1.0 0.239 0.479 0.479 - 0.958
Thermal Con- ductivity W/m °C 0.10 - 0.20 0.55 - 0.70 0.025 - 0.05 0.025 - 0.070 0.02 - 0.06
Btu/h ft °F 0.057 - 0.116 0.32 - 0.40 0.014 - 0.029 0.0144 - 0.040 0.116 - 0.35
  Latent Heat kJ/kg 200 - 1000 1200 - 2100      
Btu/lb 86 - 430 516 - 903      
    Viscosity cP ** 1.8 @ 0 °C 0.02 - 0.05 0.01 - 0.03 0.01 - 0.03
0.57 @ 50 °C      
0.28 @ 100 °C      
0.14 @ 200 °C      

Air Cooled Heat Exchanger Energy Unit Conversions

Unit Multiply To Obtain
  1 joule/kilogram/K = J/(kg.K) = 1 joule/kilogram/°C = J/(kg.°C) 0.000239 Calorie /gram/°C = cal/(g.°C)
0.001 Joule/gram/°C = J/(g.°C)]
1.0 Joule/kilogram/°C = J/(kg.°C)
0.001 kilojoule/kilogram/°C = kJ/(kg.°C)
0.000239 kilocalorie /kilogram/K = kcal/(kg.K)
0.000239 kilocalorie /kilogram/°C = kcal/(kg.°C)
0.000239 Btu/pound/°F = Btu/(lb.°F)
0.102 kilogram-force meter/kilogram/K
0.000423 Btu/pound/°C = Btu/(lb.°C)
   
  1 Btu/s 106.6 kgf.m/s
1.056 kW
0.3002 Ton (refrig)
1.435 hp
778.8 ft.lbf/s
  1 Btu/pound/°F = Btu/(lb°F) 4186.8 joule/kilogram/°C = J/(kg.°C)
1.8 Btu/pound/°C = Btu/(lb.°C)
1.0 kilocalorie /kilogram/°C = kcal/(kg.°C)
4186.8 joule/kilogram/K = J/(kg.K)
4.1868 kilojoule/kilogram/K = kJ/(kg.K)
4.1868 joule/gram/°C = J/(g.°C)
426.9 kilogram-force.meter/kilogram/K
4.1868 kilojoule/kilogram/°C = kJ/(kg.°C)
778.2 pound-force.foot/pound/°R