[ \dotm = \frac7.5 \times D^2.8 \times (P_cond - P_evap)^0.5L^0.5 ]
This is a comprehensive technical review of . Technical Review: Capillary Tube Sizing for R134a Refrigerant 1. Introduction The capillary tube (cap tube) is a fixed restriction expansion device widely used in small refrigeration systems (domestic refrigerators, freezers, dehumidifiers, and bottle coolers). For R134a (1,1,1,2-Tetrafluoroethane), which has been a dominant refrigerant in these applications for decades, accurate sizing is critical. A "Tabla de Capilares" provides the necessary relationship between tube length, internal diameter (ID), operating pressures/temperatures, and cooling capacity. Tabla De Capilares Para R134a
Capacities are nominal for high-back-pressure compressors. Always adjust for actual operating conditions. Table 2: Correction Factors (Multipliers) | Parameter | Condition | Factor | |-----------|-----------|--------| | Condensing Temp | +10°C (from 55°C) | 1.18 | | Condensing Temp | -10°C (from 55°C) | 0.85 | | Evaporating Temp | +10°C (from -23°C) | 1.32 | | Evaporating Temp | -10°C (from -23°C) | 0.75 | | Subcooling | 2 K (instead of 5 K) | 0.90 | | Subcooling | 8 K (instead of 5 K) | 1.07 | 4. Empirical Sizing Formulas for R134a Several correlations exist. A widely used simplified formula (based on ASHRAE Research Project 578) for R134a mass flow rate (ṁ) in kg/h is: [ \dotm = \frac7
Obtain a validated table from a reputable source (e.g., Danfoss, Parker, or ASHRAE Handbook – Refrigeration Chapter), and always incorporate a 10–15% safety margin in capacity selection. Always adjust for actual operating conditions