2016 ASHRAE Winter Conference

Energy efficiency, heat recovery and cost efficiency of commercial refrigeration systems still have a large development potential for systems applying R744 as the only refrigerant. The system architecture has to be in the focus with respect to increase the system efficiency when these units are operated at elevated ambient temperatures. The objective of this work is to investigate the energy required for different R744 commercial refrigeration systems at various locations in all the global continents compared to a HFC404A configuration.

Due to the recent governmental regulations to limit the use of high GWP refrigerants, new lower GWP refrigerants are currently under evaluation by the industry. These new refrigerants exhibit promising thermal performance when compared to widely used refrigerants such as R404A. In this presentation, thermal properties and actual system performance data for non-flammable and mildly-flammable low-GWP refrigerants are discussed in details, showing energy efficiency and environmental benefits of using these new refrigerants in commercial refrigeration. In addition, changes in equipment design and control to further improve energy efficiency are explored, with focus on systems with moderate glide refrigerants.

It is well  know that when dealing with R744 high ambient temperatures can create design issues including loss of efficiency or reliability.  Currently a majority of the design effort is being focused on adapting the refrigeration circuit design to adapt to higher ambient conditions.  What if we could de-couple the impact of ambient temperature from the system entirely?  This seminar will explore a case study of an operating hybrid geothermal transcritical CO₂ installation from design, installation and  through first year of operation.

Refrigerants are essential to multitudes of HVAC&R processes in the commercial sector. Although meant to be contained within various equipment types, their usage inevitably leads to leakage, which may directly contribute to ozone depletion and/or global warming. In response, CO2 rose as a viable alternative in refrigerated beverage vending machines. Simultaneously, federal regulators continue to update minimum/high-efficiency standards for equipment efficiency, and are additionally exploring a proposal for prohibiting certain high-GWP refrigerants. This presentation will discuss the findings of a high-level evaluation, conducted by TTC, on the efficiency and performance of a CO2 vending machine and the applicable standards.