2018 IIAR Technical Papers
Colorado Springs, Colorado
40th Annual Meeting

A Refrigeration System Using Air as Working Fluid
Author: Troy Davis

The manufacturer has developed a refrigeration system using air (R-729) as the working fluid. Air, a natural refrigerant, has no impact on the environment unlike conventional fluorocarbon refrigerants. The air refrigeration system produces the extremely low temperatures (-58°F/-50°C to -148°F/- 100°C) required in cold-storage warehouses and pharmaceutical and cryogenic applications. The system, which mainly comprises an integrated centrifugal compressor and expander, regenerative heat exchanger, and primary cooler, can save more than 30% of energy for the room cooling load when compared with conventional refrigeration systems that use fluorocarbon refrigerants, as shown in the following site example. This paper offers a brief history of industrial refrigeration and some basic refrigeration concepts before reporting on an air-based system and its applicable use.

Large Scale Flammability and Explosivity Testing of Ammonia: Impact on Siting Studies and Risk Assessments
Author: Scott G. Davis, John L. Pagliaro, and Tom F. Debold, Matthijs van Wingerden and Kees van Wingerden

Large-Scale Flammability and Explosivity Testing of Ammonia: Impact on Ammonia Safety in Refrigeration Applications (2018) - Understanding the fire and explosion risks of flammable refrigerants is critical for their safe use in practical applications. Considerable efforts have gone into understanding these risks for the more flammable fluids (e.g., propane and methane), which are highly reactive as described by their laminar burning velocities (LBV)—typically around 40 cm/s. However, significantly less work has been performed to understand the fire and explosion risks of mildly flammable fluids, such as ammonia, which are much less reactive, having LBVs less than 10 cm/s. This is particularly concerning given that the current push to minimize human impact on the climate has led to an increase in the use of mildly flammable compounds and refrigerants such as ammonia and other low global warming potential (GWP) working fluids with LBVs less than 10 cm/s.
Ultra-Low Charge Ammonia Refrigeration in Food Retail: Successful Case Study
Authors: Karthick Kuppusamy and Augusto J.P. Zimmermann

Ultralow-Charge Ammonia Refrigeration in Food Retail: A Successful Case Study (2018) - The refrigeration segment particularly for food retail segment has been moving towards adoption of alternative systems that use low Global Warming Potential (GWP) and Ozone Depletion Potential (ODP) refrigerants. One of the key requirements is to do with little to no impact to their bottom line or disruption of operations. For such retail operators and supermarket owners, NH3/CO2 cascade system is one of the options to be future proof in terms of regulations on refrigerant use and achieving energy savings at the same time. This paper will describe in details all the aspects of designing, installing, commissioning and certification of energy savings for a medium size supermarket in southeastern USA. The subject of the case study comprises of a cascade refrigeration system with the low side using CO2 as a refrigerant and with duplicate top sides. The duplicate top sides, one with ammonia and another one using HFC 407A refrigerant allows for same store comparison of energy consumption and reliability of the systems. The low side of the system is common between the duplicate top sides. The system is fully instrumented to allow for energy comparison and optimization studies on operating parameters and set points. The study shows an average 22% energy savings when operating with the ammonia top side vs. R407A. Another aspect of the paper is to outline design approach to minimize the charge to only 53lbs of ammonia for a total of 70TR of refrigeration capacity. The paper also delineates an oil system design and the safety precautions utilized to mitigate risks to the end user regarding reliability and ammonia releases.
Best Practices in Managing an PSHA NEP or EPA GDC Inspection
Author: Edward Johnson

This paper gives ammonia refrigeration professionals guidance on Occupational Safety and Health Organization (OSHA) National Emphasis Program (NEP) or United States Environmental Protection Agency (EPA) General Duty Clause (GDC) inspections and the regulations and documents that govern them. Specifically, the paper discusses the following items: 
1. How facilities are chosen for a NEP inspection. 
2. What comprises the NEP inspection process, including a. Pre-inspection document requests (Appendix A provides examples), b. Responses to an inspector’s arrival at your facility, c. OSHA priority for conducting inspections, d. Opening conference, e. The inspection, f. Closing conference, g. Opportunity for an informal conference with OSHA, and h. Types of citations and maximum penalties for each. 
3. What comprises EPA GDC inspections, including a. The GDC as defined under the Clean Air Act, Section 112(r)(1); b. Who the GDC applies to; c. Facility obligations under the GDC; d. How the EPA chooses where to inspect; e. The emphasis on ammonia refrigeration; f. Frequently cited discrepancies; and g. Best practices for GDC facilities. To summarize, this paper
• Will provide enhanced awareness of how facilities are chosen,
• Provide examples of documents typically requested during an NEP inspection,
• Gives a better understanding of best practices for the inspection process,
• Define the GDC and identify typical discrepancies found, and
• Gives clear guidance on preparing for NEP and GDC inspections.

Employee Engagement as an Indicator of PSM Program Success or Failure
Author: Jodie Richter

Process safety management (PSM) programs are only as successful or compliant as the company’s employees’ level of engagement. PSM audits often indicate that employee implementation is the leading factor in a program’s success or failure. This paper shares insights gained from interacting with site personnel and company management during PSM audits and presents recommendations based on the author’s strategic human resources experience in implementing employee relations programs that increase employee engagement. The subject matter is written with the typical processing plant refrigeration department in mind, but the management strategies can be applied throughout all industries and at all employee levels. Recommendations were developed to promote the manager’s leadership autonomy outside of the organization’s formal human resource practices or policies.
Emergency Response in an Ammonia Facility
Author: Craig Slininger, CIRO
 This paper explores steps to consider prior to an emergency incident, focusing on developing a working relationship between local emergency response departments and your organization’s internal teams to develop mutual confidence and skills. All members, from each group, work together toward a common goal.
Application of Bow Tie Diagrams to Understanding Threats and Barriers in Industrial Refrigeration

Author: Martin Timm, PE

Bow tie diagrams are widely used in industries with recognized hazards, including petrochemicals, aviation, health care, and the nuclear industry. They graphically communicate threats and the barriers that prevent these threats from turning into undesired events and consequences. The name “bow tie” describes the appearance of the diagram, wherein a “top event” is arranged in the center of a page with a fault tree feeding into it from the left showing threats and an event tree flowing out to the right showing potential consequences. This paper briefly reviews the literature on the bow tie method and presents an example for loss of containment of ammonia to show how the industrial refrigeration industry can use bow tie diagrams. The example also illustrates that results of various risk studies can be presented in a format readily understood and used by facility personnel and can be directly related to requirements in IIAR standards.

Energy and Function Analysis of Hot Gas Defrost in Ammonia Refrigeration Systems

Author: Niels Vestergaard and Morten Juel Skovrup

Ammonia has over decades proven its value as an effective refrigerant, but choosing the right—and correctly sized—defrost and control methods is important to ensure high efficiency. Traditionally one of two methods for controlling drainage of the evaporator during hot gas defrost is used: pressure control, which keeps the pressure in the evaporator constant during defrost, or liquid drain control, which uses a float valve to drain condensed liquid from the evaporator. Each method’s energy consumption is quite different, as the pressure-control method bypasses a certain amount of hot gas during the defrost period. This paper is based on results from a research project focusing on energy savings potential during hot gas defrost in ammonia refrigeration systems (ELFORSK project 347-030). In the ELFORSK project, an ammonia pumped circulation system was built at the Danish Technological Institute, enabling detailed measurements of the defrost system. Two methods of hot gas defrost were tested and analyzed (pressure control and liquid drain method), as were three evaporator designs (bottom feed, top feed, and side/bottom feed). A simulation model was also developed and validated using the measurements. This paper will focus on the design requirements of the two most common defrost methods for ammonia systems (pressure control and liquid drain method) and describe the design requirements for both systems to obtain the highest efficiency. The efficiency of the two defrost systems will be analyzed and compared.

Facts and Myths Associated with Choosing the Right Construction Materials for Evaporative Condensers
Author: Zan Liu, PhD and Robert Cunningham

Evaporative condensers are used almost exclusively in industrial refrigeration systems, especially with ammonia applications in the United States. Their unparalleled heat rejection efficiency, associated with the lowest first costs, comes from evaporative cooling, which means that the inside of the condenser constantly exposed to aerated water for most of its operation time. Choosing the right construction materials is critical, not only for protecting the equipment investment and maintaining maximum efficiency, but also for safety and structural integrity. The most common materials used in evaporative condensers are galvanized steel [hot-dipped galvanized carbon steel (HDG) and hot-mill-galvanized carbon steel (HMG)] and 300 series austenitic stainless steel (SS). Galvanized steel has been, and still is, the dominant material due to its good corrosion resistance and heat transfer characteristics. However, 300 series SS has become a viable alternative over the past five years, thanks to lower costs due to improved control of alloy composition and other manufacturing cost reductions. Even though evaporative condensers have been widely used for decades, the changing backdrop of complexity and variation of water chemistry and metallurgy and the multiple environmental restraints encountered have resulted in a poor understanding and a lack of guidelines on when upgrading to SS makes sense.
Stainless Steel Piping in Industrial Refrigeration
Author: Eric W. Teale, P.E.

Stainless steel piping and pipeline components are increasingly specified in industrial refrigeration applications due their corrosion resistance. Stainless steel is not a problem-free material, however, and a proper understanding of stainless steel is required to determine its proper use in industrial refrigeration. This paper describes stainless steel, its history and properties, corrosion of stainless steel, welding of stainless steel, and quality assurance/quality Control issues associated with the installation of stainless steel.

2018 Programa en español

Diseño de evaporadores para expansión directa (DX) con amoníaco
Author: Bruce I. Nelson, P.E.

Los diseñadores y operadores de sistemas de refrigeración por amoníaco con evaporadores de expansión directa deben tener un conocimiento básico de las limitantes y características únicas del amoníaco para operar exitosamente estos sistemas. Este documento tratará las consideraciones de diseño especiales requeridas para los evaporadores de amoníaco con expansión directa, tanto en la tecnología tradicional como en los nuevos diseños de evaporadores que permiten trabajar a bajas temperaturas.

Condensadores enfriados por aire y condensadores adiabáticos para sistemas de refrigeración con amoníaco como alternativa a los condensadores evaporativos
Author: Ing. Ricardo Iván García López

La problemática actual referente a la disponibilidad de agua para consumo industrial, reflejada en el constante aumento en su precio y las regulaciones de su disposición final, nos lleva a buscar alternativas para reducir su consumo. Los condensadores evaporativos son dispositivos necesarios para la industria de la refrigeración; sin embargo, las soluciones alternativas como los condensadores enfriados por aire, o bien los condensadores adiabáticos, se han implementado con gran éxito, lo cual ha llegado a reducir el consumo de agua e incluso a eliminarlo en su totalidad de los sistemas de refrigeración industriales al operar con amoníaco. El presente trabajo realiza un claro análisis de cómo, cuándo y dónde las alternativas tecnológicas de enfriamiento por aire o enfriamiento adiabático tienen cabida para el eficiente diseño de sistemas de refrigeración industriales con el objetivo de reducir o eliminar totalmente el consumo de agua para enfriamiento.

Influencia a causa de la formación de escarcha en el evaporador y sus implicaciones termodinámicas 
Author: Ing. Christian Ali Muñoz

El objetivo de este estudio es establecer los fundamentos termodinámicos que rigen la formación de escarcha en los evaporadores para así poder estudiar sus implicaciones energéticas y para poder establecer criterios que permitan mejorar los rendimientos del descongelamiento por gas caliente (HGD) de los sistemas de refrigeración industrial. Se analizarán las prácticas comunes en los sistemas de refrigeración implementadas para la eliminación de la escarcha en los evaporadores de descongelamiento por gas caliente (HGD), tomando en consideración la geometría del serpentín del evaporador, la configuración de las aletas, la temperatura del refrigerante, los tiempos estimados para cada fase del deshielo y la energía necesaria para derretir la escarcha acumulada. La última parte del estudio se centra en las consideraciones que deben hacerse para calcular las estimaciones de los costos incurridos en un ciclo de deshielo, producto del flujo másico de refrigerante y de la energía requerida para dicho fin.