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Investigations of the performance of a heat pump with internal heat exchanger

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Abstract

The aim of this study was to develop a mathematical model with lumped parameters to investigate the energetic parameters of the heat pump with an internal heat exchanger (IHX). The developed mathematical model is validated with 25 tests using R134a as a working fluid. The results show that the maximum prediction error between the modeled and experimental results for the COP is 7.06%. The main objective of this paper was to investigate the COP value of a heat pump as a function of the efficiency of the internal heat exchanger and present a new equation to calculate the COP value. When the efficiency of IHX was increased from 0.65 to 0.95, the COP value increased by 5.41% under the conditions of minimum evaporation − 20 °C and maximum condensation temperature 90 °C.

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Abbreviations

A :

Heat transfer area (m2)

C :

Characteristic constant of the TEV valve (–)

Cp :

Specific heat at constant pressure (J kg−1 K−1)

COP:

Coefficient of performance (–)

D :

Diameter (m)

h :

Enthalpy (J kg−1)

Nu:

Nusselt number (–)

\(\dot{m}\) :

Mass flow rate (kg s−1)

P :

Compressor power (kW)

Pr:

Prandtl number (–)

Rc:

Capacity ratio (–)

Re:

Reynolds number (–)

Q :

Heat transfer rate (kW)

T :

Temperature (K)

U :

Overall heat transfer coefficient (W m−2 K−1)

α :

Heat transfer coefficient (W m−2 K−1)

η :

Compressor efficiency (–)

λ :

Thermal conductivity (W m−1 K−1)

ρ :

Density (kg m−3)

ε :

Efficiency of the IHX (–)

r :

Refrigerant

c :

Condenser

o :

Evaporator

liq:

Liquid phase

vap:

Vapor phase

cw:

Cooling water

hw:

Hot water

in:

Inlet

out:

Outlet

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  1. University of Dunaújváros, Táncsics Mihály 1/a, Dunaújváros, 2400, Hungary

    Róbert Sánta

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  1. Róbert Sánta
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Sánta, R. Investigations of the performance of a heat pump with internal heat exchanger. J Therm Anal Calorim 147, 8499–8508 (2022). https://doi.org/10.1007/s10973-021-11130-5

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