Flammable Refrigerants The Evolving Impact on Codes With appreciation to Danfoss North America and Tidwell Consulting Today’s Goal Explore the changing refrirgerant environment and its potential affect on codes. Courtesy: Johnson Controls (www.johnson controls.com) 2016 ICC Annual Conference Education Programs Kansas City, MO 1 Learning Objectives • Identify the environmental and code issues associated with the refrigerant gas changes. • Describe simple refrigeration physics, terminology and chemistry. • Identify current public safety code requirements and issues. • Identify proposed changes in refrigeration gases. Challenge . Traditional refrigerants are being banned or phased down . Potent greenhouse gases . Both air conditioning and refrigeration . Alternatives are available, but many are flammable . Codes currently do not allow their use 2016 ICC Annual Conference Education Programs Kansas City, MO 2 Part I: Refrigeration Concerns Why Change? GLOBAL WARMING POTENTIAL Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFC) INFLUENCE WARMING GLOBAL 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2016 ICC Annual Conference Education Programs Kansas City, MO 3 Montreal Protocol Phase-out Begins INFLUENCE January 1, 1989 WARMING GLOBAL WARMING POTENTIAL Chlorofluorocarbons (CFCs) and GLOBAL Hydrochlorofluorocarbons (HCFC) 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Hydrofluorcarbons GLOBAL WARMING POTENTIAL Hydrofluorocarbons (HFCs) Phase-out Begins INFLUENCE January 1, 1989 WARMING GLOBAL 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2016 ICC Annual Conference Education Programs Kansas City, MO 4 Global Demand Developing Countries Refrigeration High estimate and A/C for Demand World Low estimate Developing Developed Countries 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Source: National Oceanic and Atmospheric Administration (NOAA) EU: Move down to low-GWP refrigerants 100% INFLUENCE WARMING GLOBAL 20% 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2016 ICC Annual Conference Education Programs Kansas City, MO 5 US: GWP Proposed Phaseout (EPA) Supermarkets Remote Condensing Units Small vending machines Large vending machines Standalone low temperature devices Central air conditioners ? 2017 2018 2019 2020 Potential ICC Effects • IBC 1006.2.2.2 – Egress from refrigeration machinery rooms • IMC Chapter 11 – Mechanical Refrigeration • IFC 606 – Mechanical Refrigeration • Equipment testing • Emergency controls • Treatment and flaring systems 2016 ICC Annual Conference Education Programs Kansas City, MO 6 Part II: Refrigeration Physics Refrigeration Physics . Newton’s First Law of Thermodynamics . Conservation of energy: Energy cannot be created or destroyed in chemical reaction U=Q‐W Where: U = change in internal energy Q = heat added to the system (energy in) W = Work done by the system (energy out) 2016 ICC Annual Conference Education Programs Kansas City, MO 7 Heat Properties . Always moves from warmer to cooler surface . Moves by radiation, convection or conduction . When a refrigerant boils it absorbs heat . When a refrigerant condenses, it releases heat . Heat by a fluid (refrigerant) ‐‐ as it changes from a liquid to a gas ‐‐ lowers the temperature of the objects around it. Mechanical Refrigeration Cycle . Compressor pressurizes refrigerant gas Condenser, where it Draws heat from the rejects heat to refrigerated space outdoors and liquefies Moves through valves where it expands into a gas 2016 ICC Annual Conference Education Programs Kansas City, MO 8 Mechanical Refrigeration: Operating Scheme (Simplified) Refrigerated space Usually outdoors Fan Mechanical Refrigeration: Definitions • Compressor – Mechanical equipment that raises refrigerant pressure Courtesy: Danfoss.com • Condensing Unit -- Assembly of a compressor, condenser, fan motor, controls and a mounting plate Courtesy: Copeland Refrigeration Units 2016 ICC Annual Conference Education Programs Kansas City, MO 9 Mechanical Refrigeration: Definitions • Expansion valve -- Adjusts refrigerant flow and pressure to satisfy all load conditions. • Refrigerant -- Liquid or gaseous cooling medium Courtesy: Danfoss Mechanical Refrigeration: Definitions •CFC – Chlorofluorocarbon •HFC -- Hydrofluorocarbon • HCFC -- Hydrochlorofluorocarbon 2016 ICC Annual Conference Education Programs Kansas City, MO 10 Mechanical Refrigeration: Definitions • Specific heat • Amount of heat per unit mass required to raise the temperature by one (1) degree Celsius (1.8F). • Used to calculate capacity requirements for refrigerating known quantities of product • Latent heat • Amount of heat absorbed or released by a substance undergoing a change of state (such as ice changing to water or water to steam) at constant temperature and pressure • Occurs in evaporator and drives the cooling process Mechanical Refrigeration: Definitions • Azeotrope • Blend of two or more refrigerants with similar boiling points that act as a single fluid. • May exhibit unique and unexpected properties • Zeotrope • Mixture of two or more refrigerants with different boiling points. • Never mixes chemically, predictable properties • Evaporates/condenses of temperature range called “glide” 2016 ICC Annual Conference Education Programs Kansas City, MO 11 Mechanical Refrigeration: Units • Refrigerant ton – A measure of cooling capacity; not refrigerant. • The energy removal rate that will freeze one short ton of water at 0 °C (32 °F) in one day. • Historically defined was approximately 11,958 Btu/hr (3.505 kW), and has now been conventionally redefined as exactly 12,000 Btu/hr (3.517 kW) • One ton of refrigeration is equal to 3024 kilo-calories per hour. – Equals 12,000 BTU/ hr divided by 2.204 (pounds per kilogram) divided by 1.8 (°C to °F). Courtesy: Livescience.com Mechanical Refrigeration: Units • Most residential A/C units capacity range: Tons kW Btu/hr 1 to 53.5‐ 17.5 12,000‐60,000 Courtesy: AC2015.com • Large industrial chiller systems up to: Tons kW Btu/hr Up to 800 2,800 9,600,000 Courtesy: excaliburlpa.co.uk 2016 ICC Annual Conference Education Programs Kansas City, MO 12 Mechanical Refrigeration: Units • For code purposes, refrigerants are measured in pounds – Unit of liquid weight – Refrigerants typically have density >1 • Heavier than water • Densities lessen at higher temperatures – Based on internal volume of the refrigeration system • Volume x liquid density at specific temperature = pounds in system – Check the system label. Mechanical Refrigeration: Side Note • For response purposes, refrigerants’ vapor density should be considered • Most refrigerant leaks occur as vapor – Vapor density >1 = vapor sinks – Vapor density < 1 = vapor rises Courtesy: US Chemical Safety Board 2016 ICC Annual Conference Education Programs Kansas City, MO 13 Mechanical Refrigeration: Pounds Recharging Vessels Courtesy: Summit Refrigerants 2016 ICC Annual Conference Education Programs Kansas City, MO 14 Part III: Refrigerant Chemistry Optimal Refrigerant • Should have low boiling point and low freezing point. • Must have low specific heat and high latent heat. – high specific heat decreases the refrigerating effect per pound of refrigerant, and, – high latent heat at low temperature increases the refrigerating effect per pound of refrigerant. 2016 ICC Annual Conference Education Programs Kansas City, MO 15 Refrigerant Composition Prefix Represents Examples R Refrigerant R22, R134a, R717 May include: RC317 C Chlorine Chloroheptafluorocyclobutane R22B1 B Bromine Bromodifluoromethane RFE‐36 F Fluorine Hexafluoropropane R134a H Hydrogen 1,1,2,2‐Tetrafluoroethane RC318 C Carbon Octafluorocyclobutane RE170 E Ether Dimethylether Refrigerant Nomenclature Numbering Chemistry Examples Series 000, 100, 200 Hydrocarbon‐based HCFC‐22, HFC 134a, R290 (propane) 400 Zeotropes R‐404A 500 Azeotropes R‐507A 600 Organic R‐600a (isobutane) 1000 Unsaturated organics HFO‐1234yf* *Will replace HFC‐134a in automobile air conditioning 2016 ICC Annual Conference Education Programs Kansas City, MO 16 Refrigerant Nomenclature • Legacy refrigerant numbering scheme (R-XXXX) describes chemical composition R(efrigerant) >Number of double carbon bonds > Carbon atoms > Hydrogen atoms > Fluorine atoms Hydrocarbons/Derivatives * R134a : Tetrafluoroethane – CH2FCF3 Carbon Hydrogen Fluorine Nof double carbon bonds R Atoms Atoms Atoms (Placeholder omitted when zero) (Minus 1) (Plus 1) (N/molecule) R 0134 Remaining bonds not accounted for are chlorine. *a = Isomer stability. R22: Chlorofluoromethane – CHClF2 Carbon Hydrogen Fluorine Nof double carbon bonds R Atoms Atoms Atoms (Placeholder omitted when zero) (Minus 1) (Plus 1) (N/molecule) R ???? Zero double bonds 1‐1= 0 1+1 = 22 (omitted) (omitted) 2016 ICC Annual Conference Education Programs Kansas City, MO 17 Zeotropic . Zeotropic . Respective refrigerant number and mass proportions . Number designates components, but not amount (molecules) of each . Identifying number in 400 series, assigned arbitrarily (in order of approval) . R407A . (R32/R125/R134a): (20/40/40) . R407B . (R32/R125/R134a): (10/70/20) R-500 Series . Two-component refrigerant mixtures . a CFC and an HFC, or, . a CFC and an HCFC . Exception: R-507 . a mixture of two HFCs 2016 ICC Annual Conference Education Programs Kansas City, MO 18 Organics/Inorganics . Organics: given in numerical order in 600 series . R600a : Isobutane C4H10 . Inorganics: assigned in 700 series by adding molecular mass to 700 . R717: Ammonia NH3 ASHRAE Safety Groups Flammability Toxicity Group Classification Group A Group B Lower Toxicity Higher Toxicity