1、 UFC 4-826-10 10 July 2002 UNIFIED FACILITIES CRITERIA (UFC) DESIGN: REFRIGERATION SYSTEMS FOR COLD STORAGE APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 4-826-10 10 July 2002 UNIFIED FACILITI
2、ES CRITERIA (UFC) DESIGN: REFRIGERATION SYSTEMS FOR COLD STORAGE Any copyrighted material included in this UFC is identified at its point of use. Use of the copyrighted material apart from this UFC must have the permission of the copyright holder. U.S. ARMY CORPS OF ENGINEERS NAVAL FACILITIES ENGINE
3、ERING COMMAND (Preparing Activity) AIR FORCE CIVIL ENGINEER SUPPORT AGENCY Record of Changes (changes are indicated by 1 . /1/) Change No. Date Location _ This UFC supersedes NAVFAC Design Manual 3.04 Refrigerated Systems for Cold Storage dated 1 Aug 1986. Provided by IHSNot for ResaleNo reproductio
4、n or networking permitted without license from IHS-,-,-UFC 4-826-10 10 July 2002 FOREWORD The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departme
5、nts, the Defense Agencies, and the DoD Field Activities in accordance with USD(AT but the largest application is for the refrigeration and freezing of foods. Refrigerated systems provide much lower temperatures than comfort air conditioning systems. The design, selection, and construction of a refri
6、geration system is different and can be more intensive than that for a comfort air conditioning system. For this reason, the refrigeration industry has evolved into a separate and distinct industry. 1-3 PRIMARY VOLUNTARY CONSENSUS STANDARD REFERENCE. This UFC adopts the latest edition of American So
7、ciety of Heating, Refrigeration, and Air Conditioning Engineers, Inc. (ASHRAE) Publications listed below as the primary voluntary consensus standard for the Tri-services refrigeration systems for cold storage. ASHRAE Handbook Refrigeration 1-4 SECONDARY VOLUNTARY CONSENSUS STANDARD REFERENCES. This
8、UFC adopts the latest edition of the standards listed below as the secondary voluntary consensus standard for the Tri-services refrigeration systems for cold storage. ASHRAE Standards encompass halocarbon and ammonia refrigeration systems. International Institute of Ammonia Refrigeration (IIAR) refe
9、rs to ammonia systems exclusively. ASHRAE 15 ASHRAE Handbook Applications ASHRAE Handbook Fundamentals ASHRAE Handbook HVAC Equipment and Systems ANSI/IIAR STANDARD 2 1-1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 4-826-10 10 July 2002 IIAR
10、Ammonia Refrigeration Piping Handbook 1-5 CONFLICTS IN CRITERIA. If any conflicts arise between the services safety criteria and ASHRAE 15, the most stringent requirement shall prevail. If a facility is located off of military owned sites, where local jurisdictional authority has control and code re
11、quirements that are more stringent than those herein, the local jurisdictional authority will prevail. 1-6 SUSTAINABLE DESIGN. It is the policy of the tri-services to incorporate sustainability concepts in the design of all facilities and infrastructure projects to the fullest extent possible, consi
12、stent with budget constraints and customer requirements. This policy applies to renovations and alteration projects as well as new construction; applies to projects regardless of funding source or amount; applies to projects for all customers; and applies to design associated with all procurement me
13、thods, including design/build. For further information, see NAVFAC Planning and Design policy Statements PDP 98-01, 98-02, 98-03 on the Construction Criteria Base (CCB) at http:/www.ccb.org, and Sustainable Design at http:/www.efdlant.navfac.navy.mil/lantops_04/designguides.htm. Also see Corps of En
14、gineers ETL 1110-3-491, Sustainable design for military facilities, at http:/www.ccb.org/. 1-7 REFERENCES. Refer to Appendix A for references applicable to this document. 1-8 DEFINITIONS Azeotropic A precise refrigerant mixture or blend of substances that has properties differing from either of the
15、two constituents. Design-Build Contractor furnishes a designed and constructed facility, usually from a performance specification. Direct Expansion System - A refrigerant system that has the refrigerant entering an expansion valve and only vapor leaves the evaporator. Glide The absolute value of the
16、 difference between the starting and ending temperatures of a phase change process by a refrigerant. Halocarbon Refrigerant that is a hydrocarbon derivative that contain one or more of the halogens bromine, chlorine, fluorine, or iodine; hydrogen may also be present. Liquid Recycle System A refriger
17、ant system that has liquid refrigerant in the evaporator in amounts larger than can be evaporated and obtains higher efficiencies due to higher heat transfer of wetted surfaces. Plan and Specify Engineering firm furnishes a design, then the design is competitively bid. 1-2 Provided by IHSNot for Res
18、aleNo reproduction or networking permitted without license from IHS-,-,-UFC 4-826-10 10 July 2002 Owner Tri-service arm having the responsibility of operating and maintaining the subject facility. 1-3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-U
19、FC 4-826-10 10 July 2002 CHAPTER 2 REFRIGERATION SYSTEM DESIGN REQUIREMENTS 2-1 GENERAL. Design refrigerated systems for cold storage to provide safety, economy, and reliability. Refrigeration design is a specialized field. The design of cold storage refrigerated systems should be performed by an ex
20、perienced refrigeration design engineer. A “plan and specify” or a “design-build” arrangement can perform the refrigeration design. Design-build has been the trend of the refrigeration industry. In many cases, equipment manufacturers have significantly supported the refrigeration design. 2-2 SAFETY.
21、 Safety is paramount. Safety is critical in the design, construction and operation of refrigeration systems for cold storage, especially with ammonia systems. Refrigeration systems safety standards must meet ASHRAE 15. ASHRAE 15 specifies safe design, construction, installation, and operation of ref
22、rigeration systems by establishing safeguards for life, limb, heath and property and prescribing safety standards. This includes, but is not limited to, occupancy classification, restriction on refrigeration use, installation restrictions, design and construction of equipment and systems, and operat
23、ion and testing. Consider equipment selection and its placement for safe accessible maintenance. A safety review of the engineered design and equipment layout is recommended with participation from the owners site operations and maintenance (O 1 compressor for each cooler), the designer may elect to
24、 show only the individual components and their relative layout or schematic with no pipe sizes or slopes. For these types of systems, it will be the Contractors responsibility to submit shop drawings and calculations to completely define the entire system based on the equipment to be provided. Refer
25、 to the ASHRAE Handbook Refrigeration, in the following chapters: Liquid Overfeed Systems System Practices of Halocarbon Refrigerants System Practices for Ammonia Refrigerant Secondary Coolants in Refrigeration Systems 2-6.3.1 Refrigerants. The selection of a refrigerant impacts the project economic
26、s and safety. The selection, design, construction, and operation of a refrigeration system must meet ASHRAE 15. Occupancy, and restrictions on refrigerant quantity and usage are also detailed on the drawings. Product, occupancy, or other criteria might require a ”low-probability system” for the refr
27、igeration system. Low-probability systems are designed so that if a leak occurred, the refrigerant cannot enter the occupied space. Most indirect systems are considered “low-probability systems”. 2-3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UF
28、C 4-826-10 10 July 2002 An indirect system has a secondary coolant, such as brine, that is cooled or heated by the refrigeration system. A comprehensive list of refrigerants and refrigerant blends are listed in Table 1 and Table 2 respectively of ASHRAE 34. The most common commercially available ref
29、rigerants for use in cold storage are ammonia (R-717) and the halocarbons (R-22, R-134a, R-404a, and R-507). R-404a is not recommended because it is a nonazeotropic mixture. A leak in a refrigeration system with a nonazeotropic mixture would change the composition resulting in a glide that would bec
30、ome unpredictable. A system leak could cause off performance that ultimately would require a complete refrigerant replacement. R-134a is not recommended for large capacity systems because the density is low and would require larger volume equipment. Ammonia is corrosive, hazardous, and can damage pr
31、oduct when released in large quantities. But ammonia is considerably cheaper, much more efficient as a refrigerant, and has easier oil separation capabilities. Halocarbons have a lower toxicity limit than ammonia. All refrigerants can be injurious or even fatal in high enough concentrations and shou
32、ld be handled carefully. If ammonia is not ruled out as a refrigerant, the life cycle analysis will most likely suggest an ammonia system for large (typically above 464.5 square meters (5000 square feet) cold storage refrigeration applications. Selecting a refrigerant for cold storage design is a fu
33、nction of the refrigeration design temperature and the equipment available. Lubrication oil management becomes critical at lower temperatures, especially when the oil is lighter than the refrigerant. The application temperatures of refrigerants overlap, but the current trends are the following: Ammo
34、nia (R-717) and R-22 have similar temperature applications for approximately 34.4 degrees C (-30 degrees F) and above. R-507and R-404a have similar temperature applications for approximately 60 degrees C to 0 degrees C (-76 degrees F to 32 degrees F) R-134a has temperature applications for approxima
35、tely 17.8 degrees C (0 degrees F) and above. 2-6.3.1.1 Ammonia. Ammonia is a self-alarming substance that is distinguished by its pungent odor. Persons exposed to ammonia vapors well below the permanently damaging levels will not voluntarily stay in such areas. Flammability limits of ammonia at atmo
36、spheric pressure are at least 100 times greater than the amount willingly tolerated. An ammonia-air mixture in an iron flask does not ignite below 651.1degrees C (1204 degrees F). The US Department of Transportation classifies ammonia as a nonflammable compressed gas for the purpose of transportatio
37、n. Ammonia is rated a Group B-2 in ASHRAE 34; that classifies ammonia as more toxic than most other refrigerants. Safety requirements are heightened for ammonia, thus the need for special care and attention to safety details in ammonia systems. Since ammonia is lighter than air, adequate ventilation
38、 is the best means of preventing accumulation. The challenge with ammonia is to control the magnitude of and promptly correct a leak, in order to avoid injury to people and damage to property and product. It is important that 2-4 Provided by IHSNot for ResaleNo reproduction or networking permitted w
39、ithout license from IHS-,-,-UFC 4-826-10 10 July 2002 personnel understand the properties of ammonia and be thoroughly trained in its use and application. 2-6.3.1.2 Halocarbons. Halocarbons are halogenated hydrocarbons that contain one or more of the halides: chlorine, bromine, fluorine, or iodine.
40、Halocarbons are typically rated a Group A-1 in ASHRAE 34; that is a lower toxicity and flammability than ammonia. Halocarbons are widely used because they are considered a safe approach to refrigeration. Economically, halocarbons are significantly more expensive and not as efficient as ammonia. 2-6.
41、3.2 Designed Mechanical Refrigeration Systems. The selection and design of a mechanical refrigeration system should be economical, safe, reliable, and simple. A design should be indicative of the refrigeration industrys trends, with emphasis on simplicity and low maintenance. There are essentially t
42、wo refrigerant system designs utilized in the cold storage refrigeration market, i.e., direct expansion and liquid recirculation. The dominant design is a field constructed ammonia liquid recirculation system utilizing screw compressors and evaporative condensers. Large systems can have thousands of
43、 kilograms of refrigerant. If an ammonia refrigerant system exceeds 4536 kg (10,000 pounds) of ammonia, OSHA 29 CFR 1910 requires implementing a Process Safety Management program (PSM) and a Risk Management Plan (RMP). This entails written procedures, environmental impact plan, etc. This would requi
44、re staff and other operating requirements that can be very expensive to implement and maintain. There is an O that includes retail display cases, walk-in storage coolers, household refrigerators and freezers, and commercial icemakers. Small refrigeration systems may have their design needs met with
45、unitary systems. Unitary units are recommended for small applications due to the typical benefits over field-assembled units. These benefits are lower capital investment, higher reliability of factory assembled equipment, and comprehensive warranties. 2-6.4 Equipment Selection. The refrigeration ind
46、ustry relies heavily on equipment manufacturers. Refrigeration equipment manufacturers provide expertise and information regarding equipment and design. Finalizing the selection of equipment should be compatible with the equipment manufacturers recommendations. Installing new technological advances
47、in equipment is encouraged, but installing prototypes or new unproven technology is not recommended. 2-6.4.1 Materials of Construction. Most common ferrous and copper base metals can be used with halocarbons. Not recommended are magnesium, zinc, and aluminum alloys containing more than 2% magnesium
48、in contact with the refrigerant. Most common ferrous metals can be used with ammonia. Copper and alloys containing copper, brass, or alloys containing copper in contact with the ammonia refrigerant should not be used. 2-6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 4-826-10 10 July 2002 Contractors often install halocarbon refrigerant systems with the more stringent ammonia specifications for construction efficiencies. Ammonia components are typically more expensive but some halocarbon systems can be competitive with the
