Refrigeration Formulas

Overview

Engineering reference data for Refrigeration Formulas in basics.

Key Formulas

Ohm's Law

$V = IR$

Voltage = Current × Resistance.

Newton's Second Law

$F = ma$

Force = mass × acceleration.

Conservation of Energy

$E_{in} = E_{out} + \Delta E_{stored}$

Energy balance.

Variables

Symbol	Description	Unit
$V$	Voltage	V
$I$	Current	A
$R$	Resistance	Ω
$F$	Force	N
$m$	Mass	kg
$a$	Acceleration	m/s²

Compression Performance Metrics

The compression horsepower required for a refrigeration system can be calculated from the system's capacity and COP.

Horsepower per Ton: $p = \frac{4.715}{\text{COP}}$ where $p$ is the compressor horsepower per ton of refrigeration (hp/Ton) and COP is the coefficient of performance.

System Displacement & Efficiency

Compressor Displacement is required to move the necessary mass of refrigerant: $d = \frac{c \cdot v}{\text{NRE}}$ where $d$ is displacement (ft³/min), $c$ is capacity (Btu/min), $v$ is specific volume of suction gas (ft³/lb), and NRE is the net refrigeration effect (Btu/lb).

Volumetric Efficiency compares actual to theoretical refrigerant mass flow: $\mu = 100 \cdot \frac{w_a}{w_t}$ where $\mu$ (%) is efficiency, $w_a$ is actual weight flow, and $w_t$ is theoretical weight flow.

Compression Ratio

A key indicator of compressor stress and efficiency loss: $CR = \frac{p_h}{p_s}$ where CR is the compression ratio, $p_h$ is absolute discharge pressure (psia), and $p_s$ is absolute suction pressure (psia).

References

• Original Source