🌡️ Refrigeration System Calculator

Comprehensive cooling load, refrigerant properties, and COP calculations

Purpose: Calculate cooling loads, refrigerant cycle performance, compressor sizing, and system efficiency based on standard vapour-compression thermodynamics and heat transfer principles.

System Parameters

Cooling Load Parameters

Compressor & Heat Exchanger Design

Thermodynamic Properties

Evaporator Pressure: -
Condenser Pressure: -
Pressure Ratio: -
Mass Flow Rate: -

Cooling Load Analysis

Sensible Heat Load: -
Latent Heat Load: -
Total Cooling Load (with Safety Factor): -

System Performance

Theoretical COP (Carnot): -
Actual COP (Cycle): -
Compressor Power (Elec.): -
Energy Efficiency Ratio (EER): -

Sizing & Verification

Compressor Swept Volume: -
Evaporator Area: -
Condenser Area: -
Condenser Heat Rejection: -
Heat Balance Error: -
COP = Refrigerating Effect / Compressor Work
Q = U × A × LMTD

Actions

Technical Notes

Variable Definitions:
  • Evaporator Temperature (Tevap): Saturation temperature at evaporator pressure (refrigerant side).
  • Condenser Temperature (Tcond): Saturation temperature at condenser pressure (refrigerant side).
  • Superheat / Subcooling: Degrees above/below saturation at compressor suction / condenser outlet.
  • Cooling Load: Envelope + ventilation/infiltration + people + internal loads, with diversity and safety factor.
  • COP (Cycle): Refrigerating effect divided by compressor work (thermodynamic COP, not seasonal).
  • EER: COP converted using 1 W ≈ 3.412 Btu/hr (EER = 3.412 × COP).
  • UA/LMTD, U-value, Area: Heat-transfer screening via Q = U·A·LMTD using user-specified LMTD and U.
Formulas / Logic:
  • Saturation pressure P_sat(T): estimated using simplified correlations for quick screening (kPa).
  • Cooling load: Q_total = (Q_sensible + Q_latent) × diversity × safety factor.
  • Refrigerating effect: q_L = h1 − h3 (kJ/kg).
  • Compressor work: w = (h2 − h1) where h2 is based on isentropic efficiency η_is (screening).
  • Mass flow: ṁ = Q̇_L / q_L (kg/s).
  • Carnot COP: COP_Carnot = T_evap(K) / (T_cond(K) − T_evap(K)).
  • Heat exchanger sizing: A = Q̇ / (U·LMTD) (SI units).
  • Heat balance check: Q̇_cond ≈ Q̇_evap + Ẇ_comp.
Assumptions / Notes:
  • This calculator is a preliminary screening tool. For design, use validated refrigerant property software/tables (e.g., REFPROP) and vendor compressor maps.
  • Refrigerant property correlations here are approximate and may deviate significantly near critical region, at very low temperatures, or for blends (glide).
  • CO₂ (R744): above ~31°C, cycle may be transcritical; treat results as indicative only.
  • ASHRAE/ISO refrigeration and load-calculation methods are more detailed (envelope U-values, infiltration, humidity/latent). Use project standards for final sizing.
  • U-values and LMTD depend strongly on exchanger geometry, fouling, approach temperatures, and flow arrangement; vendor rating is required for final area.
  • Efficiencies: Use vendor data when available. Typical ranges: η_is 70–85%, η_vol 80–95%, motor 85–95%.
  • Standards / references (context): ASHRAE Handbook—Refrigeration; ISO 5149 (refrigeration safety); EN 378 (systems and heat pumps); general vapour-compression thermodynamics texts.
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