Experimental studies on transcritical CO₂ heat pump system for simultaneous water cooling and heating application

ABSTRACT

An in-house transcritical CO₂ heat pump experimental facility was developed for simultaneous cooling and heating of water. Hand-operated (Needle) valve is used as an expansion device to control the gas cooler pressure and mass flow rate of refrigerant. The tests were conducted to study the performance of the system and components at various operating conditions. Four independent input operating variables and four output variables are considered for investigation. The factorial experimental design was employed to achieve the optimum set of experiments. Taguchi L9 array is used to design experiments for chosen variables and results were analyzed by using response surface methodology (RSM).

It is observed that system charging pressure and degree of expansion valve opening affect the system performance greatly. Maximum cooling and heating output from the system was recorded as 3.8 kW and 6.6 kW, respectively, and the corresponding system COP obtained was 3.1. Empirical correlations are developed employing RSM technique to predict the system performance.

KEYWORDS:

• Hand-operated (needle) valve
• transcritical
• response surface modeling
• heat pump
• CO₂

Acknowledgments

Authors are thankful to TEQIP II, a world bank-assisted project, to support the present research work for developing the test facilty.

Additional information

Funding

This work was supported by the Technical Education Quality Improvement Programme II which is a project of Government of India assisted by World Bank .