Heat and Mass Transfer

, Volume 54, Issue 3, pp 803–812 | Cite as

Experimental evaluation of refrigerant mass charge and ambient air temperature effects on performance of air-conditioning systems

  • Mahdi Deymi-Dashtebayaz
  • Mehdi Farahnak
  • Mojtaba Moraffa
  • Arash Ghalami
  • Nima Mohammadi


In this paper the effects of refrigerant charge amount and ambient air temperature on performance and thermodynamic condition of refrigerating cycle in the split type air-conditioner have been investigated. Optimum mass charge is the point at which the energy efficiency ratio (EER) of refrigeration cycle becomes the maximum. Experiments have been conducted over a range of refrigerant mass charge from 540 to 840 g and a range of ambient temperature from 27 to 45 °C, in a 12,000 Btu/h split air-conditioner as case study. The various parameters have been considered to evaluate the cooling rate, energy efficiency ratio (EER), mass charge effect and thermodynamic cycle of refrigeration system with R22 refrigerant gas. Results confirmed that the lack of appropriate refrigerant mass charge causes the refrigeration system not to reach its maximum cooling capacity. The highest cooling capacity achieved was 3.2 kW (11,000 Btu/h). The optimum mass charge and corresponding EER of studied system have been obtained about 640 g and 2.5, respectively. Also, it is observed that EER decreases by 30% as ambient temperature increases from 27 °C to 45 °C. By optimization of the refrigerant mass charge in refrigerating systems, about 785 GWh per year of electric energy can be saved in Iran’s residential sector.



EER improvement


condenser subcooling


average energy saving per year for 20% of installed air-conditioners with different capacities yr)/yr)

ΔW\( {t}_i \),

energy saving per year for air-conditioner with cooling capacity i yr)/yr)

ΔẆ\( {t}_i \),

power saving for air-conditioner with cooling capacity i (kW)


density (kg/m3)


specific humidity of air, kg/kg of dry air


area (m2)


coefficient of performance

cos φ,

power factor


dry bulb temperature (°C)


energy Efficiency Ratio




enthalpy of air entering the indoor side, kJ/kg of dry air


enthalpy of air leaving the indoor side, kJ/kg of dry air


total current


refrigerant mass charge (m)


pressure (bar)


total cooling capacity


temperature (°C)


ambient air temperature


velocity (m/s)


Indoor air-flow rate, m3/s


specific volume of air at point of measurement of air-water vapour mixture, m3/kg


total voltage


wet bulb temperature (°C)


total input power



The authors would like to thank Iran Energy Efficiency Organization (IEEO-SABA) for providing air-conditioning laboratory services and their technical and financial support during this project.


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringHakim Sabzevari UniversitySabzevarIran
  2. 2.Young Researchers and Elite Club, Rasht Branch, Islamic Azad UniversityRashtIran
  3. 3.Iran Energy Efficiency Organization (IEEO-SABA)TehranIran

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