Plate Heat Exchanger Calculator
Example Data Table
| Input | Example Value | Unit | Purpose |
|---|---|---|---|
| Hot flow | 2.5 | kg/s | Sets hot heat capacity rate |
| Hot temperatures | 90 to 60 | °C | Defines heat removed from hot stream |
| Cold flow | 3.0 | kg/s | Sets cold heat capacity rate |
| Cold temperatures | 25 to 50 | °C | Defines heat gained by cold stream |
| Clean U value | 2200 | W/m²·K | Estimates heat transfer rate per area |
| Area per plate | 0.35 | m² | Converts required area into plate count |
Formula Used
Hot duty: Qh = mh × Cph × (Thi − Tho)
Cold duty: Qc = mc × Cpc × (Tco − Tci)
Counterflow LMTD: ΔT1 = Thi − Tco, ΔT2 = Tho − Tci
Parallel flow LMTD: ΔT1 = Thi − Tci, ΔT2 = Tho − Tco
Log mean temperature difference: LMTD = (ΔT1 − ΔT2) / ln(ΔT1 / ΔT2)
Effective U value: Ue = 1 / ((1 / Uclean) + Rf)
Required area: A = Q / (Ue × F × LMTD)
Active plates: Nactive = ceiling(A with margin / area per plate)
Reynolds number: Re = ρ × v × Dh / μ
Pressure drop estimate: ΔP = (f × L / Dh + local allowance) × ρv² / 2
How to Use This Calculator
- Enter hot stream flow, inlet temperature, outlet temperature, and fluid properties.
- Enter cold stream flow, inlet temperature, outlet temperature, and fluid properties.
- Add clean U value, fouling resistance, correction factor, plate area, and geometry.
- Select counterflow or parallel flow.
- Select the duty basis. Average duty is useful when both sides are known.
- Press Calculate to view the result above the form.
- Use CSV or PDF download buttons to save the calculation report.
Plate Heat Exchanger Calculation Guide
Overview
A plate heat exchanger moves heat through thin corrugated plates. Two fluids pass on opposite sides of each plate. The large contact area gives high heat transfer in a compact frame. This page uses common design equations for a worked sizing example.
Heat Duty
Start with the heat duty. The hot side duty equals mass flow multiplied by heat capacity and temperature drop. The cold side duty uses the temperature rise. A balanced design gives similar values on both sides. A large mismatch points to wrong data, heat loss, phase change, or unit errors.
Temperature Difference
Next calculate the log mean temperature difference. Counterflow normally gives a stronger driving force than parallel flow. The correction factor reduces the ideal value for port losses, pass effects, and layout limits. The effective heat transfer area comes from duty divided by overall coefficient and corrected LMTD.
Plate Count
Plate count is then estimated from active area per plate. End plates often do not transfer heat, so the tool adds allowance. The result is a practical starting point, not a final mechanical selection. A manufacturer may adjust plate pattern, gasket material, ports, and frame size.
Hydraulic Check
Hydraulic checks matter. Narrow channels raise velocity and heat transfer. They also increase pressure drop. The calculator estimates Reynolds number, friction factor, velocity, and pressure loss on each side. These values help decide whether a design is gentle, turbulent, or too restrictive.
Input Quality
Use clean inlet data. Select fluids with realistic heat capacity, density, viscosity, and conductivity. Enter fouling resistance when deposits are expected. Food, cooling water, glycol, and dirty process streams often need extra margin. A larger fouling value lowers the effective overall coefficient and increases required area.
Engineering Use
This calculator is useful for study, preliminary sizing, and comparison. It can show how duty changes when flow changes. It can show why a small temperature approach needs more surface. It can also compare counterflow and parallel cases quickly. Final equipment design should include vendor limits, gasket ratings, pressure code rules, cleanability, and allowable pressure drop. Treat the result as an engineering estimate.
Final Review
Record every assumption before sharing the report. Small property changes can move area and pressure loss. Always compare several cases, because plate exchangers are sensitive to approach temperature, channel gap, and flow distribution changes.
FAQs
1. What is a plate heat exchanger?
It is a compact heat exchanger made from stacked plates. Hot and cold fluids flow through alternating channels. Heat passes through the metal plates without mixing the fluids.
2. What does this calculator estimate?
It estimates heat duty, LMTD, effective U value, heat transfer area, plate count, flow velocity, Reynolds number, and pressure drop for a preliminary plate exchanger design.
3. Why is LMTD important?
LMTD represents the average thermal driving force between hot and cold streams. A higher LMTD needs less area. A low LMTD requires more plates for the same heat duty.
4. Why does counterflow often perform better?
Counterflow keeps a stronger temperature difference across more of the exchanger length. This usually improves LMTD and reduces the surface area needed for the same duty.
5. What is fouling resistance?
Fouling resistance allows for deposits on heat transfer surfaces. It lowers the effective U value. Higher fouling usually increases the required plate area.
6. Is the pressure drop result final?
No. It is an estimate based on simplified friction assumptions. Final pressure drop depends on plate pattern, port size, gasket layout, pass arrangement, and vendor data.
7. Why add a safety margin?
A safety margin allows for uncertain properties, future fouling, manufacturing limits, and operating variation. It helps avoid undersizing during early design work.
8. Can this replace vendor sizing?
No. Use it for learning and preliminary checks. Final exchanger selection should be confirmed with manufacturer software, pressure ratings, gasket limits, materials, and service conditions.