Statistical optimization of Closed Loop Pulsating Heat Pipe parameters with R-410a and nanorefrigerant in air conditioning applications

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ABSTRACT The present investigation is an attempt to study the effect of refrigerant with nanoparticles against conventional refrigerant in closed loop pulsating heat pipe (CLPHP). Here, a customized CLPHP was used in this study and nanorefrigerant was prepared using R-410a with graphene nanoparticles in distilled water as the novel working fluid. The process parameters for CLPHP with both refrigerants, optimized using the statistical tool Response Surface Methodology based on central composite design, were inclination angle (θ°) ranging between 85 and 95, and power (W) ranging between 90 and 110. In this study, thermal conductivity (Rth), thermal resistance (k) and temperature difference (Δ T) between evaporator and condensor were analyzed. The optimized parameters for standard refrigerant were found to be: inclination angle 92° and power 104 W whereas for nanorefrigerant the parameters were 88° and 102 W. The yields in terms of Rth, k and T for refrigerant were 0.015°C/W, 6284.33 W/mK and 10°C and those for nanorefrigerant were 0.0025°C/W, 32376.72 W/mK and 18°C. This investigation revealed that the R2 values were approximately 100% in both cases illustrating that the statistical evaluation was true to the experimental model and befitting the same. The complete results exhibited that in both cases thermal conductivity increased while thermal resistance decreased. Also, differences in temperature between evaporator and condensor was larger in CLPHP with nanorefrigerant while it was lower in CLPHP with R-410 alone. Hence, the overall study suggested that the efficacy of R-410a with graphene nanoparticles was 80.05% better than that of lone R-410a in CLPHP. In conclusion, this experiment evinced the positive utilization of nanorefrigerant as working fluid in CLPHP for air conditioning applications.