A status update on committee activities to update ASHRAE Standard 15 will set up the workshop discussion to follow. The relationships, interactions and relative timing between ASHRAE 15, building codes and US EPA SNAP is reviewed.

A status update on committee, working group and technical panel activities to update various UL standards. Interconnection and process between UL, CSA, ANCE, CANENA, and IEC is reviewed.

Transitioning of refrigerants involves a great deal of consideration, particularly for new product implementation. OEM’s tests units to make sure system performance is at least maintained. Sometimes new refrigerant developed for OEM operation doesn’t always mean it will work effectively for retrofit situations. One particular detail that needs investigation, is will the retrofit refrigerant work effectively with lubricant that was formerly used in the unit. Previous refrigerant transitions showed some additional manipulation of the lubricant was needed. Today there is another transition to using lower GWP refrigerants which will once again require evaluation of the lubricant in retrofit situations.

Servicing with low GWP refrigerants is becoming common in the HVAC&R industry due to the phase out of conventional refrigerants. It is important to follow best practices such as refraining from mixing refrigerants and using the recommended lubricants while considering that HFOs will exhibit a different nature than HFC or HCFC refrigerants. This session covers the impact of common contaminants that may influence the system performance and reliability of some very low GWP refrigerants containing unsaturated molecules such as R-1234yf and R-1233zd(E). In addition, stabilizers which can prevent the deterioration of performance due to contaminants is discussed.

The search for replacements for HCFC and HFC based refrigerants such as R-22 and R-404A, being phased out globally due to stratospheric ozone depletion and global warming potential issues, has led to the development of low GWP HFO blend alternatives, such as R-449A. This presentation includes the retrofit procedure for HFO refrigerants in low and medium temperature commercial refrigeration systems that were originally designed for HCFC and HFC refrigerants. Also, data obtained during actual system conversions, including compatibility with seals/lubricants as well as operational and energy performance is reported.

Flammability risk, in the event of a leak, can be lowered by reducing the potential for forming a refrigerant/air mixture that can reach the lower flammability limit (LFL) in the event of a leak into a confined space. The determination of effective room area and space volume has become critical to safety. This paper will describe an approach for determination effective room area, including methods to utilize adjacent connected spaces. Computational fluid dynamic (CFD) analysis was performed to support the justification for the methodology. An approach, utilizing the principles of natural convection and forced convection will be described for determining the effective room area and volume for individual rooms and connected rooms for unventilated spaces.

This paper presents details of a study which investigates the long-term thermal resistance (LTTR) performance of polyurethane insulation within discrete cold storage panels used in the US retail grocery environment. The research seeks to better define the potential benefit of extending the productive life of the insulation through longer cold storage service or through recycling into another insulative material. A total of ten U.S. retail chain grocery store sites were semi-randomly selected for the extraction of polyurethane panel specimens from decommissioned cold storage structures. Thermal performance of the cold storage panel specimens was determined by using the ASTM C518-10 Standard Test Method.

The need for refrigeration in the retail industry and specifically in supermarkets, currently accounts for around 30% to 60% of the total energy consumed in stores. A key characteristic of this consumption, is the high amount of low-grade (i.e., low-temperature) heat rejected by the condensation units to the ambient air. This paper focuses on the transcritical CO₂ (R744) refrigeration cycles and aims to assess whether the use of a water-cooled condenser rejecting heat to the soil via an intermediate closed water-circuit, can reduce the energy consumption, while also considering the economic implications of this modification.

Two-phase ejectors are an attractive replacement for conventional expansion devices due to the opportunity to recover expansion work that can be used to improve cycle efficiencies. This presentation covers important aspects of ejector modeling and will provide basic design guidelines. The different ejector components are explained and typical efficiency and performance metrics are introduced. The presentation also elaborates on different control options that enable the use of ejectors for efficient part load operation and operation at off-design.

Two-phase ejectors are an attractive replacement for conventional expansion devices due to the opportunity to recover expansion work that can be used to improve cycle efficiencies. Optimal use requires careful design with regard to the full operating envelope, including attention to manufacturability considerations. This seminar covers important aspects of manufacturing for ejector systems and their resulting impact on system design.

CO2 Natural Refrigerant has been introduced in container transport refrigeration systems. Working in a wide range of ambient temperatures, meeting various set temperature requirements and temperature management are key to success. The background of the changes to natural refrigerant CO2 and technologies used in CO2 container refrigeration systems to meet product requirements is presented, and performance comparisons with alternate refrigerant systems is discussed. Additionally, follow on technological advances such as those in the areas of CO2 ejectors are reviewed, including their potential benefits and impacts to the current system design.

Today’s societal demands to control climate change are forcing HVAC&R equipment designers to consider new lower GWP refrigerants, some of which are slightly flammable under certain conditions. This paper supports setting a safety factor as low as 2 to 1 (50% of LFL) when setting the charges limits for A2L flammable refrigerants depending on the HVACR products application refrigerant charge and application height. Computational fluid dynamic (CFD) analysis was performed to support the justification of setting the safety factor. Numerous fast leak scenarios, 4 min leaks, were evaluated at various heights, room areas and refrigerant charge sizes. Maximum refrigerant charges for a large number of ASHRAE 34 classified refrigerants will be summarized for comparison purposes at various LFL endpoints.

Demands to control climate change are forcing HVAC equipment designers to consider new lower GWP refrigerants to replace traditional higher global warming potential (GWP) refrigerants, for example R134a and R410A. Understanding the environmental tradeoffs of using these new low GWP alternatives in HVAC products is becoming well understood but what uncertainty remains in understanding how they impact the on building sustainability. This paper provides an understanding of the impacts on total building sustainability through using building model simulations employing products using new lower GWP alternatives R513A and R452B to replace R134a and R410A.

There is significant interest in the adoption of low global warming potential (GWP) refrigerants. However, the heat transfer performance of these refrigerants is not well documented. This paper investigates alternate R410A refrigerants such as R32 and R452B. Fewer than 10 papers have been located which report heat transfer and pressure drop data for R32 and no papers have been located which report heat transfer and pressure drop data for R452B. The predicted performance of low GWP R410A alternatives will be compared to baseline values for R410A and impact on evaporator and condenser design will be discussed.

In recent years, the HVAC&R industry has been evaluating low global warming potential (GWP) alternatives to refrigerants such as R410A because of rising concerns over climate change due to their high direct GWPs. The industry is working to identify candidates that optimize performance, safety (flammability), and environmental impacts (GWP). R452B and R32 are two of the candidates under consideration. This paper presents measurements of system performance made on an R410A-based 100 RT air-cooled packaged water chiller with R410A (as baseline), R452B, and R32 refrigerants. The chiller comprised scroll compressors, a brazed plate evaporator, and microchannel condenser.

This presentation examines the benefits of Evaporative Condensers/Gas Coolers (EC/GCs) where the cooling medium temperature is the Ambient Wet Bulb Temperature (AWBT) and not the ambient dry bulb temperature as is the case with air cooled gas coolers. A 1% incidence AWBT of 28°C is not exceeded in 98% of the world’s climates. At a AWBT of 28°C it is relatively easy to achieve a gas cooler CO₂ exit temperature 31°C and even 30°C at part load. This means that efficient CO₂ refrigeration may be operated all over the world with the use of EC/GCs.

Natural refrigeration technology in supermarkets is driven by growing global concerns around energy and environment. Energy efficiency, safety and reliability are key characteristics of supermarket system design. A field test is carried out on a Supermarket with ammonia system as top cycle catering to MT and LT refrigeration loads. The entire system is designed with state-of-the-art energy efficient features and ultra-low ammonia charge @ 0.75 Lbs / TR. A brief overview of design considerations and test results are presented. Superior efficiency of ammonia is demonstrated in a side by side energy study with HFC that is validated by third party.

The low GWP of natural refrigerants makes them great candidates for commercial refrigeration. An important characteristic of transcritical CO2 cycles are the substantial throttling losses that negatively impact energy efficiency at high ambient temperatures. This presentation introduces numerous ways of improving COP at demanding outdoor conditions, and the emphasis will be on utilizing two-phase ejectors. A variety of cycle options exist that allow integration of ejectors, including utilization of the recovered energy to unload the compressor, to provide cooling at different temperature levels and to improve efficiency by using the ejector to drive refrigerant overfeed in liquid recirculation cycles.

This presentation provides the final results from field testing of a packaged ammonia/carbon dioxide system installed in Irvine, CA. The unit was one of the first of its kind installed in North America and provides a glimpse at how natural refrigerants can be applied to systems where they previously were not used. The project was featured in a Feb 2016 ASHRAE Journal article.