Thermodynamic performance of automobile air conditioners working with R430A as a drop-in substitute to R134a

Abstract

The refrigerant R134a is to be phasing out soon in automobile air conditioning applications due to its high global warming potential of 1430. Hence, it is essential to identify a sustainable alternative refrigerant to phase out R134a in automobile air conditioners. This paper presents the experimental thermodynamic performance of R430A (composed of R152a and R600a, in the ratio of 76:24, by mass) as a drop-in substitute to replace R134a in automobile air conditioners. The experiments were carried out in an automobile air conditioner test setup equipped with a variable frequency drive electrical motor. During experimentation, the ambient temperature and ambient relative humidity were maintained at 35 ± 1 °C and 65 ± 5%, respectively. The compressor speed was varied in the range between 1000 and 3000 rpm. The results showed that the coefficient of performance of an automobile air conditioner working with R430A was found to be 12–20% higher with 6–11% reduced compressor power consumption when compared to R134a. The R430A has 2–6 °C higher compressor discharge temperature when compared to R134a. The physical stability of the lubricant used in the compressor was retained while operating with R430A. The maximum exergy destruction occurs in the compressor (0.28 kW for R134a and 0.24 kW for R430A) followed by evaporator (0.16 kW for R134a and 0.14 kW for R430A), condenser (0.14 for R134a and 0.12 kW for R430A) and expansion valve (0.043 kW for R134a and 0.039 kW for R430A) at a compressor speed of 1000 ± 10 rpm. The exergy destruction of the system operating with R430A was found to be 12–28% lower when compared to R134a systems due to its favorable thermo-physical properties. The total equivalent warming impact of R430A was found to be lower when compared to R134a by about 47.3%, 35% and 32.4% for LPG, petrol and diesel vehicles, respectively. The results confirmed that R430A is a good drop-in substitute to replace R134a in existing automobile air conditioning systems.

Annexure

The uncertainty of calculated performance parameters are given by:

Mass flow rate

$$ \mathop {\mathop m\limits^{ \bullet } }\limits^{.}{_{\text{r}}} = \left[ {\left( {\frac{\delta N}{N}} \right)^{2} + \left( {\frac{{\delta T_{1} }}{{T_{1} }}} \right)^{2} + \left( {\frac{{\delta T_{0} }}{{T_{0} }}} \right)^{2} + \left( {\frac{{\delta P_{1} }}{{P_{1} }}} \right)^{2} } \right]^{1/2} $$

Refrigeration effect

$$ {Q}_{\text{evaporator}} = \left[ {\left( {\frac{{\delta \mathop m\limits^{ \bullet }{_{\text{r}}} }}{{\dot{m}{_{\text{r}}} }}} \right)^{2} + \left( {\frac{{\delta T_{1} }}{{{\text{T}}_{ 1} }}} \right)^{2} + \left( {\frac{{\delta P_{1} }}{{P_{ 1} }}} \right)^{2} + \left( {\frac{{\delta T_{4} }}{{{\text{T}}_{ 4} }}} \right)^{2} + \left( {\frac{{\delta P_{4} }}{{P_{ 4} }}} \right)^{2} } \right]^{1/2} $$

Compressor power consumption

$$ {W}_{\text{compressor}} = \left[ {\left( {\frac{{\delta \mathop m\limits^{ \bullet }{_{\text{r}}} }}{{\mathop m\limits^{ \bullet }{_{\text{r}}} }}} \right)^{2} + \left( {\frac{{\delta T_{1} }}{{T_{ 1} }}} \right)^{2} + \left( {\frac{{\delta P_{1} }}{{P_{ 1} }}} \right)^{2} + \left( {\frac{{\delta T_{2} }}{{T_{ 2} }}} \right)^{2} + \left( {\frac{{\delta P_{2} }}{{P_{ 2} }}} \right)^{2} } \right]^{1/2} $$

Coefficient of performance

$$ \mathop {\text{COP}}\limits = \left[ {\left( {\frac{{\delta Q_{\text{evaporator}} }}{{Q_{\text{evaporator}} }}} \right)^{2} + \left( {\frac{{\delta W_{\text{compressor}} }}{{W_{\text{compressor}} }}} \right)^{2} } \right]^{1/2} $$

Exergy destruction in compressor

$$ \mathop {\text{Ex}}\limits^{\cdot}{_{\text{dest,comp}}} = \left[ {\left( {\frac{{\delta \mathop m\limits^{ \bullet }{_{r}} }}{{\mathop m\limits^{ \bullet }{_{r}} }}} \right)^{2} + \left( {\frac{{\delta T_{1} }}{{T_{ 1} }}} \right)^{2} + \left( {\frac{{\delta P_{1} }}{{P_{ 1} }}} \right)^{2} + \left( {\frac{{\delta T_{2} }}{{T_{ 2} }}} \right)^{2} + \left( {\frac{{\delta P_{2} }}{{P_{ 2} }}} \right)^{2} + \left( {\frac{{\delta T_{0} }}{{T_{0} }}} \right)^{2} + \left( {\frac{{\delta W_{\text{compressor}} }}{{W_{\text{compressor}} }}} \right)^{2} } \right]^{1/2} $$

Exergy destruction in condenser

$$ \mathop {\text{Ex}}\limits^{\cdot}{_{\text{dest,cond}}} = \left[ {\left( {\frac{{\delta \mathop m\limits^{ \bullet }{{_{\text{r}}}} }}{{\mathop m\limits^{ \bullet }{_{\text{r}}} }}} \right)^{2} + \left( {\frac{{\delta T_{2} }}{{T_{ 2} }}} \right)^{2} + \left( {\frac{{\delta P_{2} }}{{P_{ 2} }}} \right)^{2} + \left( {\frac{{\delta T_{3} }}{{T_{ 3} }}} \right)^{2} + \left( {\frac{{\delta P_{3} }}{{P_{ 3} }}} \right)^{2} + \left( {\frac{{\delta T_{0} }}{{T_{0} }}} \right)^{2} + \left( {\frac{{\delta Q_{\text{condenser}} }}{{Q_{\text{condenser}} }}} \right)^{2} } \right]^{1/2} $$

Exergy destruction in an expansion device

$$ \mathop {\text{Ex}}\limits^{\cdot}{_{\text{dest,expansion}}} = \left[ {\left( {\frac{{\delta \mathop m\limits^{ \bullet }{_{\text{r}}} }}{{\mathop m\limits^{ \bullet }{_{\text{r}}} }}} \right)^{2} + \left( {\frac{{\delta T_{3} }}{{T_{ 3} }}} \right)^{2} + \left( {\frac{{\delta P_{3} }}{{P_{ 3} }}} \right)^{2} + \left( {\frac{{\delta T_{4} }}{{T_{ 4} }}} \right)^{2} + \left( {\frac{{\delta P_{4} }}{{P_{ 4} }}} \right)^{2} + \left( {\frac{{\delta T_{0} }}{{T_{0} }}} \right)^{2} + \left( {\frac{{\delta Q_{\text{expansion}} }}{{Q_{\text{expansion}} }}} \right)^{2} } \right]^{1/2} $$

Exergy destruction in an evaporator

$$ \mathop {\text{Ex}}\limits^{\cdot}{_{\text{dest,evaporator}}} = \left[ {\left( {\frac{{\delta \mathop m\limits^{ \bullet }{_{\text{r}}} }}{{\mathop m\limits^{ \bullet }{_{\text{r}}} }}} \right)^{2} + \left( {\frac{{\delta T_{4} }}{{T_{4} }}} \right)^{2} + \left( {\frac{{\delta P_{4} }}{{P_{4} }}} \right)^{2} + \left( {\frac{{\delta T_{1} }}{{T_{1} }}} \right)^{2} + \left( {\frac{{\delta P_{1} }}{{P_{1} }}} \right)^{2} + \left( {\frac{{\delta T_{0} }}{{T_{0} }}} \right)^{2} + \left( {\frac{{\delta Q_{\text{evaporator}} }}{{Q_{\text{evaporator}} }}} \right)^{2} } \right]^{1/2} $$

Exergy destruction in a system

$$ \mathop {\text{Ex}}\limits^{\cdot}{_{\text{dest,system}}} = \left[ {\left( {\frac{{\delta W_{\text{compressor}} }}{{W_{\text{compressor}} }}} \right)^{2} + \left( {\frac{{\delta Q_{\text{condenser}} }}{{Q_{\text{condenser}} }}} \right)^{2} + \left( {\frac{{\delta Q_{\text{expansion}} }}{{Q_{\text{expansion}} }}} \right)^{2} + \left( {\frac{{\delta Q_{\text{evaporator}} }}{{Q_{\text{evaporator}} }}} \right)^{2} } \right]^{1/2} $$