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Optimal Charge Amount for Different Refrigerants in Air-to-Water Heat Pumps

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Iranian Journal of Science and Technology, Transactions of Mechanical Engineering Aims and scope Submit manuscript

Abstract

This paper describes an experimental study on the heat pump performance and compressor suction pressure, in order to find out the optimal refrigerant charge amount for different refrigerants. Independent of the choice of refrigerant, environmental and safety problems can be reduced by detecting the optimal amount of refrigerant charge in the heat pumps or refrigeration systems. In this investigation, a laboratory air-to-water heat pump was built to find out the charge effects on the coefficient of performance and heating capacity for three different gases including R22, R134a and R404a. Gas injection was done gradually into the system, and results were obtained and recorded at each stage. It was shown that refrigerant overcharge and undercharge decrease performance of the unit. Although heating capacity increases gradually, compressor work increases with additional charge and there must be an optimum charge amount to obtain the maximum coefficient of performance.

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Abbreviations

COP:

Coefficient of performance

GWP:

Global warming potential

ODP:

Ozone depletion potential

p :

Pressure (kPa)

\(\dot{W}\) :

Compressor power (W)

T :

Temperature (°C)

C p :

Specific heat capacity (J kg−1 K−1)

h :

Refrigerant enthalpy (kJ kg−1)

\(\dot{Q}\) :

Heat transfer rate (W)

AWHP:

Air-to-water heat pump

I :

Electric current (A)

U :

Voltage (V)

\(\dot{m}\) :

Mass flow rate (kg s−1)

k :

Thermal conductivity (W m−1 k−1)

g :

Gravity (m s−2)

hc:

Heat transfer coefficient (w m−1k−1)

D :

Condenser diameter (m)

r :

Condenser radius (m)

L :

Condenser length (m)

B :

Coefficient of thermal expansion (k−1)

v :

Kinematic viscosity (m2 s−1)

\(\dot{e}\) :

Energy loss (W)

a, e:

Air passing through evaporator

w, c:

Water passing through condenser

evap:

Evaporator

comp:

Compressor

cond:

Condenser

r:

Refrigerant

a:

Air

w:

Water

HP:

Heat pump

as:

Asbestos

o:

Outer

i:

Inner

s:

Condenser surface

in:

Inlet

out:

Outlet

T:

Total

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Acknowledgments

This project was supported by the Research Project Foundation of the Ataturk University (Project No. BAP-2013/105). The authors gratefully acknowledge the support of this study.

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Authors and Affiliations

  1. Department of Mechanical Engineering, Atatürk University, 25240, Erzurum, Turkey

    Faraz Afshari, Omer Comakli & Sendogan Karagoz

  2. Department of Mechanical Engineering, Kafkas University, Kars, Turkey

    Nesrin Adiguzel

Authors
  1. Faraz Afshari
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  2. Omer Comakli
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  3. Nesrin Adiguzel
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  4. Sendogan Karagoz
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Correspondence to Faraz Afshari.

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Afshari, F., Comakli, O., Adiguzel, N. et al. Optimal Charge Amount for Different Refrigerants in Air-to-Water Heat Pumps. Iran J Sci Technol Trans Mech Eng 40, 325–335 (2016). https://doi.org/10.1007/s40997-016-0028-2

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  • DOI: https://doi.org/10.1007/s40997-016-0028-2

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