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2006 IIAR Technical Papers
28th Annual Meeting
System Design for Industrial Ammonia/CO2 Cascade Installations
Author: Ole Christensen
Restrictions in using CFC, HCFC, and even HFC refrigerants are tightening in most countries. Potentially, this leaves natural refrigerants, such as ammonia, CO2, propane, butane, etc. as the only practical choices. However, hydrocarbon refrigerants such as propane and butane are highly flammable and explosive and, as such, will probably never be widely used refrigerants. For most industrial refrigeration installations, the choice will be between systems using ammonia alone and systems using cascaded ammonia/CO2. In addition, many countries/states are increasingly restricting ammonia charge sizes, and many end users do not want ammonia in work, process, or storage areas. As a result, ammonia/CO2 cascade systems are becoming a popular solution all over the world. This paper describes various system design solutions for cascade systems. Selection of components, sizing of valves, relief valves pipes and vessels are discussed. Finally, the paper discusses safety precautions for operating and servicing ammonia/CO2 cascade systems.
Ammonia Refrigeration Management: Fine Tuning the People Machine
Author: Lawrence F. (Tex) Hildebrand and Vern Sanderson
Each year the industry spends millions of dollars attempting to fine-tune ammonia refrigeration equipment. Vibration analysis, rebuilds, oil changes, and temperature adjustments are just a few examples. However, personnel issues such as labor disputes, personal problems, adverse working conditions, lack of perceived importance and mental health may potentially affect the safety and performance of ammonia refrigeration systems as well. In fact, it can be argued that the ammonia refrigeration operator is the single greatest contributing factor to system performance. In past years, refrigeration engineers took great ownership of the systems they operated. This culture not only reaped improved system performance and reliability, but cost savings as well. With rising energy costs, these potential savings can only increase. This paper shares real-life examples and philosophies to motivate employees, including the steps to achieve the ultimate goal of employee ownership of your ammonia refrigeration system.
Defrost Options For Carbon Dioxide Systems
Author: Andy Pearson
For many refrigeration systems no defrost is necessary. However, for systems with refrigerant evaporating below 0ºC [32ºF] where the evaporator is cooling air, an efficient and effective defrost is an essential part of the system. Some types of freezer also require a defrost cycle to free the product at the end of the freezing process. This paper describes the options available to system designers for carbon dioxide refrigeration systems where some traditional defrost methods cannot be used. A variety of alternative techniques are possible, each with advantages and disadvantages. Practical experience with some of the less common methods of defrost are given in the paper, and design guidance is provided.
The Real Costs of Product Freezing by Various Methods
Author: Klaas Visser
Many methods, such as salting, canning, drying, irradiation, fermentation, and freezing may be used to preserve food products. Freezing is attractive because it preserves many desirable attributes, such as nutrition, taste, texture, and shelf life, in a relatively straightforward manner. However, it requires costly infrastructure and incurs considerable financial overhead. The paper compares different freezing methods in terms of product damage and quality, weight loss, versatility, reliability, continuity, and associated building and refrigerant costs. The paper also provides owners with a useful tool to examine the merits of equipment offered in terms of overall owning and operating costs.
Direct Expansion Feed in Dual Stage Ammonia Plants: Operating Experiences in a Large Refrigerated Distribution Center
Author: Stefan S. Jensen
The performance and reliability of ammonia liquid overfeed systems are well known and documented. Documented operating experiences with large-scale, low-temperature, extended-surface, galvanized-steel air coolers designed for direct expansion feed are less frequent. The paper describes such an experience in a refrigerated distribution center in Queensland, Australia, and details the methodology and the computerized techniques employed in the design, circuiting, and performance prediction for such coolers. The evolution of the electronic expansion valve control algorithms and the operating experiences on which they are based are presented, as well as practical issues relating to oil management.
Non-Chemical Water Treatment for Evaporative Condensers
Author: John Lane
Maintaining good water quality is one of the most difficult challenges to achieving optimum system efficiency and prolonging the life of an evaporative condenser. Evaporative condensers typically have a high evaporation rate and use a relatively small volume of water, making chemical water treatment difficult. Using non-chemical devices (NCDs) to treat water in industrial refrigeration plants has several potential benefits, including reduced water consumption and elimination of the regulatory headaches, safety risks, and potential equipment damage associated with handling chemicals. NCDs may also improve system operating efficiency, often for much less money than the lifecycle cost of chemical water treatment. These issues have prompted many end users to investigate and try nonchemical water treatment devices, with varying success.
Risk Assessment on a Large Industrial Ammonia Refrigeration System in Central Copenhagen, Denmark
Author: Anders Lindborg
The paper describes a risk assessment conducted on a large industrial refrigeration system. The system contains a charge of 70 tonnes of ammonia and was originally built more than 125 years ago. It is located in the center of a European community with more than one million inhabitants. The environmental authorities asked for a quantitative analysis of the effects of a sudden release of six tonnes of ammonia. The effects of the release on the system and building are analyzed as realistically as possible. The concentrations of ammonia gas and effects on humans at a distance of 200 meters from the main building are also presented, and other local environmental effects explained.
Experience with IIAR’s Ammonia Refrigeration Management Program: Application to CalARP Requirements
Author: John C. Brown
IIAR’s Ammonia Refrigeration Management (ARM) Program is designed to help facilities manage their ammonia refrigeration systems in a safe and responsible manner. To comply with the requirements of the California Accidental Release Prevention (CalARP) Program, Ventura Foods chose to develop its own voluntary program using guidelines and templates in IIAR’s ARM Program, demonstrating that such a program could be practically implemented at a facility with limited resources. This paper describes the experiences of Ventura Foods as it implemented its own program to manage ammonia safely. Editor’s Note: The IIAR Ammonia Refrigeration Management (ARM) Program is a voluntary guideline developed to assist smaller ammonia refrigeration facilities with regulatory compliance. While this case study uses the ARM Program to comply with regulations that apply specifically to the State of California, the IIAR ARM Program is recommended for all ammonia refrigeration facilities with charges of less than 10,000 pounds. Many of the recommendations contained in this paper have been integrated into the currently published edition of the ARM Program.
Refrigeration for Controlled Atmosphere Storage of Apples in the 21st Century
Author: Kem Russell
Effective controlled atmosphere storage of apples requires specialized knowledge in three important areas: first, the storage requirements of the product; second, how to refrigerate the product; and third, how to control the atmosphere within the storage space. This paper reviews the history of apples and refrigeration systems used to cool them. Next, the paper briefly reviews methods used to control the atmosphere within a sealed storage space. Then, it presents factors to consider in calculating the refrigeration load and determining the type of refrigeration system, room design features, and control strategy to manage the refrigeration load throughout the storage life of the product.
The Joy of Ammonia Pump-Out Systems
Author: Peter Jordan and Kris Hinds
The Nestlé Prepared Foods Division facility in Springville, Utah has over 225,000 pounds of anhydrous ammonia in its refrigeration system. Over the years, this plant has undergone extensive modifications. Under normal circumstances, the transfer and pump-out of the ammonia prior to these modifications would entail lengthy downtimes resulting in loss of production and significant costs. This plant, however, has a plant-wide pump-out system that enables rapid pump-outs prior to system modifications. This paper explores the use of the ammonia pump-out system from an end user’s perspective. It reviews the history of the pump-out system including the logic used to justify the installation of the system and the costs associated with the system. Plant personnel also describe their many uses of the pump-out system emphasizing the flexibility it provides.
Best Practices in the Design, Construction, and Management of Refrigerated Storage Facilities
Author: Bryan R. Becker and Brian A. Fricke
Refrigerated storage facility design involves a variety of tasks, including planning, financing, site selection, architectural and structural design, refrigeration system design, equipment selection and installation, construction, inspection and maintenance. In addition, considerations of building and safety codes, efficient operation, and cost effectiveness make the design procedure more complex. This paper deals with a number of these issues as well as current, established trends in refrigerated facility design. Facility specifications are discussed, including storage conditions, storage capacity, storage arrangements, facility configuration and layout, location, and site planning. Basic information is presented on the design of refrigerated storage facility structures, including the design of support structures, walls, roofs, floors, doors and docks. Particular attention is given to the design of insulation and vapor retarders, including the roof/wall junction, as well as the foundation, floor heating systems and door types, sizes and seals. A discussion of refrigerated storage facility management is also presented, including commissioning and training, inspection and maintenance, life cycle costing, and energy strategies.
2006 Programa en español
Los sistemas en cascada amoníaco-CO2, desde un análisis termodinámico y sus aplicaciones en la refrigeración industrial
Author: Juan Manuel Quintanar
Los sistemas en cascada amoníaco-CO2 presentan una buena alternativa tanto en la parte técnica como en la parte económica para las aplicaciones de bajas temperaturas en los sistemas de dos etapas de compresión. El presente trabajo tiene como objetivo realizar un análisis termodinámico en un sistema en cascada utilizando el refrigerante CO2 como la primera etapa y el amoníaco como el refrigerante de la segunda etapa para una aplicación de un sistema de congelación rápida, comparándolo con un sistema tradicional de dos etapas de compresión utilizando amoníaco como refrigerante. La finalidad es presentar una alternativa confiable para el diseño de sistemas de congelación rápida y la difusión de este tipo de sistemas en cascada para una mejora en la selección del sistema a utilizar en la industria alimenticia.
Enfriando y congelando productos “LAC” –listo a comer
Author: Walter D. Gameiro, PhD ME
Este producto será consumido exactamente como sale de la planta procesadora. Entre la planta y el centro de distribución podrá en el producto LAC no haber calor suficiente en nuestras casas antes que el alimento sea consumido. Sin calor suficiente, no puede haber lugar para errores. Según el método seguido, la refrigeración requerida podrá ser distinta.
Sistema termodinámico de sobrealimentación del líquido a evaporadores, sus modalidades y aplicaciones
Author: Manuel Alarcon Lopez
El presente artículo acerca del sistema termodinámico de sobrealimentación de líquido y sus modalidades es un ejercicio de continuidad al trabajo que desarrollé en el pasado congreso internacional. Para esta ocasión, el objeto central de éste es difundir y ampliar el espectro de oportunidades que ofrece este sistema, a fin de que se puedan aplicar soluciones técnicas en la especialidad de diseño de instalaciones frigoríficas industriales. A partir del análisis de las condiciones de operación, termodinámicas y energéticas, se obtuvieron resultados técnicamente sustentados que demuestran su factibilidad técnica, representando una excelente alternativa para quien buscan sistemas de producción de frío cada vez más eficientes.
Análisis de los elementos que conducen a la optimización de un sistema de recirculación por bombeo de gases
Author: Juan Carlos A. Lage Soto
Los diseños de sistemas de refrigeración implican compromisos muy concretos que tienen que ver, primordialmente, con ahorro de energía y cumplimientos del debido respeto al medio ambiente. El refrigerante amoníaco cubre eficientemente dichos objetivos; sin embargo, este refrigerante, aunque no requiere instalaciones especiales en cuanto al riesgo de explosión, es un refrigerante incómodo e impopular en determinadas instancias. En principio hay que cuidar que las cargas de refrigerante sean razonables, que haya una separación positiva del aceite y el refrigerante y que se alcancen los mejores factores de transferencia en sus intercambiadores. Para el caso de los evaporadores, y en igualdad de condiciones, el método de sobrealimentación de líquido, o recirculación, resulta ser el más eficiente. Queremos, en este trabajo, tratar sobre los factores que lo hagan más manejable y applicable.