Refrigerants and their Responsible Use ASHRAE Position Document

THE LATEST TECHNOLOGY IN AIR CONDITIONING AND REFRIGERATION INDUSTRYENERGY ISSUES AND CLIMATE CHANGE 

NEW REFRIGERANTS, NEW EUROPEAN REGULATIONS AND CERTIFICATIONS,MOBILE AIR CONDITIONING AND REFRIGERATED TRUCKS

Politecnico of Milan 7th- 8th June 2013

Walid ChakrounASHRAE

ContentsWhat is ASHRAE Position Document

Refrigerants Overview Alternative TechnologiesIssues for Considerations

ASHRAE Position DocumentASHRAE position documents are

approved by the Board of Directors and express the views

of the Society.

Pressure - Enthalpy Diagram

Definition

“Refrigerants are the working fluids in refrigeration, air-conditioning, and heat-pumping systems. They absorb heat from one area, such as an air-conditioned space, and reject it into another, such as outdoors, usually through evaporation and condensation, respectively.”

Map of Refrigerant Change

DomesticRefrigerators& Freezers

AutomotiveAir Cond’g

Room AirConditioners

Unitary AirConditioners

& Heat Pumps

CommercialAir Cond’g &Refrigeration

Large AirConditioning

Cooling Capacity

Fractional 200 kW (50 tons)

Reciprocating

Fractional 10 kW (3 tons)

Rotary

5 kW (1.5 tons) 70 kW (20 tons)

Scroll150 kW (40 tons) 1500 kW (400 tons)

Screw

350 kW (100 tons) and up

Centrifugal

9

100101.10

2

4

6

8

10

12

14

16

18

WATER COOLED CHILLER DUTY

CFM/TON

DELT

A H, (B

tu/lb

)

POSITIVE DISPLACEMENT,ROTARY, SCROLL, RECIP, SCREW

CENTRIFUGAL

113123

11

114

124

134

152a

134a

12

500

22

502125

507

143a

410A

32

Application Considerations The refrigerant and

application determine Flow Lift

PD Compressors are ideally suited for higher lift

Centrifugal Compressors have high volumetric flow

Where Are We Now HFCs are greenhouse gases and the value of GWP quantifies this

effect on global warming-- In some applications, the “indirect” effect of producing energy is much greater than the GWP effect of the refrigerant itself.

Total equivalent warming impact (TEWI)--include both direct and indirect impacts of refrigeration systems--Life cycle climate Performance LCCP

Under the Kyoto Protocol, no specific mandates for reductions or phase out of the HFCs -European Union enacting regulations on HFCs --F-Gas Legislation-Some countries went even beyond by proposing an amendment to the Montreal Protocol to start phasing down HFC.

These developments led to renewed and increased interest in natural refrigerants and the development of new low-GWP options.

Present FactsThe process of switching to Low GWP is moving at different

speeds around the world—Challenges for High Ambient Temperature countries

Refrigerants selection and their operating systems still not based on a holistic analysis of multiple criteria- energy efficiency, system performance, potential impact on community safety, risk to personal safety, cost, and minimization of direct and indirect environmental impacts.

Some HFOs are available in limited quantities, Not yet fully tested in all applications. Some HFOs and lower-GWP HFCs have mild flammability and cost is high.

No ideal refrigerant yet. Natural refrigerants, the HFCs, the unsaturated HFCs (also known as HFOs), and possibly blends will continued to be used.

Challenges- High Ambient Temperature (TEAP, 2012)

High ambient temperatures lead to high condensing temperatures and pressures.—Consequences COPs drops 20%- 25%.

Constrains in high discharge temperature and pressure lead to the choice of “medium pressure” refrigerant such as HFC-134a or HFC-1234yf for single stage systems.

Lack of low-GWP refrigerants with a large refrigeration capacity in order to replace R-404A or HCFC-22 in single stage refrigeration systems.

Alternative Technologies Which refrigerant to use :

-The answer is very size and application dependent. 

-Selection of the correct refrigerant requires: capital cost, operating cost (including energy and maintenance), equipment size and location, operating temperatures/pressures, facility staff capability and local, national, and international regulations.  

CO2 TechnologyPressures in CO2 systems are approximately ten times

higher than those in ammonia—special equipment designs-different manufacturing process-high cost

High pressure results in high gas density, allows far greater refrigerating effect to be achieved from a given compressor.-cost effective for smaller products that requires high pressure rating.

At low temperatures (-30 to -50 oC), CO2 produces very small reductions in saturation temperature for a given pressure drop allowing higher mass flux in evaporators and suction pipes without efficiency penalties.-- Exceptionally good system performance in low temperature application

Hydrocarbon TechnologyHydrocarbon refrigerants have excellent

environmental, thermodynamic, and thermo-physical properties, however they are highly flammable.

Hydrocarbon refrigerants provide a range of boiling points with applicability from cryogenics to air conditioning.

Mostly used in European and Asian countries, used with commercial refrigeration systems including beverage and ice-cream machines, Transport refrigeration systems for trucks, Chillers in the range 0.3 – 40 tons of refrigeration

Ammonia TechnologyReadily available inexpensive, operates at

pressures comparable with other refrigerants, absorb large amounts of heat when it evaporates, zero ODP, Zero GWP, low TEWI.

Ammonia has a low boiling point (-28°F @ 0 psig), high latent heat of vaporization (nine times greater than R-12).

Ammonia is toxic effect at higher concentrations (i.e. = above 300 ppm)-self -alarming odor, easy to repair leaks, lighter than air.

Ammonia’s use in the HVAC&R industry should be expanded as regulatory and code officials become informed of its relative safety.

Ammonia TechnologyBarriers to expanding its use must be addressed:

-Some real and perceived, generally relate to human health and environmental safety, and system installation

-Continue research on topics such as handling, application, operation, control of emissions and new technology.

-Maintain and develop standards and guidelines for practical and safe application of ammonia in refrigeration systems.  

Questions Remain open Issues with natural refrigerants include flammability, toxicity, high pressures, or, in

some cases, lower operating efficiencies

Concern about the high GWP of some HFCs ---calling to reduce it. Research to extend lower-GWP HFCs into new applications.

The reduction has been proposed as a phase-down of HFC’s, however no country has formally adopted a proposal nor is it currently included in either the Kyoto or the Montreal Protocols.

At the present time, some hydrofluoroolefins (HFOs) are available in limited quantities, but they are not yet fully tested in all applications. In addition, some HFOs and lower-GWP HFCs have mild flammability.

Research is also investigating blends across these refrigerant classes to identify combinations that may optimize performance and minimize negative aspects.

End-of-life disposal of refrigeration and air-conditioning systems is another important issue. At that time, refrigerant should be recovered and recycled or disposed of safely to prevent loss of the charge to the atmosphere.

Research Recommendations balancing the safety, energy efficiency, cost, and environmental

impact for refrigerants using a consistent and comprehensive methodology across all refrigerants and system types using benchmarks like LCCP, life cycle assessment (LCA) or TEWI

advancing the design and development of refrigeration and air conditioning equipment that facilitate reduced refrigerant emissions

developing methodologies and practices to minimize or prevent refrigerant loss during installation, operation, maintenance, and decommissioning of refrigeration systems

developing new refrigerants that minimize environmental impacts and safety concerns