2001 IIAR Technical Papers
  Long Beach, CA
 23rd Annual Meeting

Proper Design of Refrigeration Machinery Rooms and Associated Spaces
Author: Brian Black

This paper is not intended to substitute a thorough review and analysis of the applicable codes for each project. It presents and summarizes some of the issues involved in the design and construction of refrigeration machinery rooms under representative and common building codes. It reflects my experience working in western states, on food processing and distribution facilities and represents my perspective as an architect. This perspective is, at best, that of a knowledgeable non-specialist. Engineers specializing in the appropriate discipline could expand significantly on most of the subjects covered. What I am offering is a coordinated, multi-disciplinary overview.
Compressor Start-up Or System Start-up
Author: Leon Breun, Jim Andrie, and Sam Gladis

Start-up is a continuous process of learning, documenting, and changing. The forms we have developed are not perfect and the service technicians who do the legwork have more to learn. Although the review process by the engineers is not perfect, the benefits are certainly worth the effort. This checklist system will give end users better performing, more efficient trouble free systems. Engineers receive the input they need to design more trouble free, efficient, and safer systems. Service technicians are able to leave the end user with the best and safest operating system possible. Although this organized start-up process has not yet become the industry standard, the obvious benefits to owners, engineers, suppliers, and service technicians make it worthy of consideration for all refrigeration system start-ups.
Gravity Separator Fundamentals and Design
Author: Todd Jekel, PhD, Douglas Reindl, PhD, P.E. and J. Michael Fisher

The objective of this paper is to review the literature on the principles governing gravitydriven separation of liquid-vapor mixtures, review design methods for separators, and develop a model that predicts separator performance given operating requirements (i.e. size or velocity, and design droplet size) subject to design constraints. The model presented can serve as a basis to establish a fundamentals-based new design method for gravity separators. It is not the purpose of this paper to develop or recommend design guidelines; rather it is a literature search and analysis to parallel existing design guidelines to ammonia. The paper summarizes landmark literature in the history of gravity separation and reviews the assumptions made in both the literature and the techniques developed in the paper. Equations of motion that define the droplet trajectories in both vertical and horizontal vessels are presented and implemented in a computer model. Results of in-depth analysis aimed at characterizing liquid vapor separation in both vertical and horizontal vessels are presented. ASHRAE recommendations for vessel sizing are quantified using the techniques developed in this paper. Other author’s recommendations for vertical vessel sizing are also analyzed and compared to the ASHRAE recommendations. A design example is presented for both vertical and horizontal vessels.
Demonstrating The Effectiveness Of Field Testing Evaporative Vapor Condensers
Author: Glenn Comisac

This paper demonstrates the practicality of conducting accurate and effective thermal performance tests in the field on evaporative vapor condensers installed at operating commercial facilities. By testing an installed evaporative vapor condenser and comparing the results to those of a closely controlled laboratory test of the same model, it was established that field testing can yield results commensurate with laboratory testing. Therefore, field testing can provide a practical and viable alternative to testing evaporative condensers in a laboratory.
Improving Performance of Ammonia Coils In Freezer Applications
Author: David J. Parkman and Todd Bradley, C.E.M.

Desiccant dehumidification is becoming more widely used in frozen food production facilities. Improving the performance, efficiency and maintainability of ammonia systems in these plants is a goal of all manufacturers. The desiccant dehumidifier reduces the latent load on ammonia evaporator coils by 99% allowing efficient sensible cooling. Maintenance issues are resolved with fewer defrost cycles and less wear and tear on parts. Cleanup crews in storage freezers are reduced or eliminated.
Charge Reduction in Ammonia Chiller Using Air Cooled Condensers with Aluminum Microchannel Tubes
Author: Predrag Hrnjak and Andrew Litch

This paper presents experimental results from a prototype ammonia chiller with an air-cooled condenser and a plate evaporator. The main objectives of the prototype were to reduce the ammonia charge and size of the system. The charge is reduced to 2.5 oz/Ton [20 g/kW]. This is lower than any currently available air cooled ammonia chiller on the market. The major contribution comes from use of microchannel aluminum tubes. Two aluminum condensers were evaluated in the chiller: one with a parallel tube arrangement between headers and “microchannel” tubes (hydraulic diameter Dh = 0.7 mm), and the other with a single serpentine “macrochannel” tube = 4.06 mm). The performances of the chiller and condensers are compared based on a standard different from other available ammonia chillers. This prototype was made and examined in the Air Conditioning and Refrigeration Center in 1998, at the University of Illinois at Urbana-Champaign.
Refrigeration and Controlled Atmosphere
Author: Josef Brettl

Following the harvest when contemplating what is best for their produce, growers have to decide what temperature, C02 and 02 levels should be used to allow maximum storage time while producing the best quality produce. The primary concerns during storage are produce performance and length of storage. The most important aspect is the control system, which evaluates the condition of the stored products. Two independent control systems are used for cooling technology and controlled atmosphere (CA) technology. Their control algorithms have no relation to the quality, maturity, storage, etc., of the produce in the cold room. Hence it is in the interest of the grower to know the behavior of the products during this time in order to guarantee longterm storage for supermarkets or wholesalers. Last year I observed the first claim to guaranteeing long-term storage. Supermarket globalization could lead to a demand for long-term storage capabilities. Conversely, with guarantees from contracting companies long-term storage could be a competitive advantage in the future. In order to guarantee produce storage, there are multiple parameters and information to process and evaluate. This information should include meteorological, nutritional, and biological behavior or respiration activity during storage time. Standard measurements of temperatures, pressures, and concentrations of the daily-required C02 volume, water, ethylene volume, and so on are also required. These parameters along with newly tested technologies, including gas adsorption, gas concentration, and sensors, make it possible to guarantee long-term storage.
NH3/H20 Absorption Refrigeration Plant for Large Capacities
Author: Helmut E. Mattes

Generally, refrigeration is generated by using compression-type refrigeration plants that are driven by electric power. However, other processes like absorption type refrigeration plants may also be applied. Unlike the compression refrigeration process, in an absorption type refrigeration plant the refrigerant vapor is not compressed mechanically but absorbed in the absorber by a suitable liquid (absorbent, multi-component mixture) and compressed in the liquid phase. Subsequently, the coolant is desorbed again from the solution by the supply of heat, and can then be condensed in the condenser like in a compression-type refrigeration plant. The system consists of a chain of heat exchangers connected in series. The electrical energy required for driving the solution pumps is only a small percent of the mechanical driving energy required for comparable, compression-type refrigeration plants.
Field Demonstration of Performance Benefits of Hydrotreated Paraffinic (Group II) Refrigeration Oils in Ammonia Systems
Author: Mark G. Dolson

Several recent contributions to the refrigeration literature describe the advantages of refrigeration oils made from hydrotreated paraffinic mineral oils, also known as Group II oils, used in ammonia refrigeration systems. These papers have presented a great deal of information on the physical and chemical properties of hydrotreated paraffinic mineral oils that should provide beneficial properties for ammonia systems when compared to the use of a conventional lubricant manufactured from naphthenic mineral oils. However, there has not been a wealth of documentation that these physical and chemical properties of hydrotreated paraffinic oils actually produce the promised advantages in ammonia refrigeration systems. This paper explores the properties of hydrotreated paraffinic oils, comparing them to the requirements for a lubricant in an ammonia refrigeration system. Field case studies are presented that show how these physical and chemical properties translate into operational benefits in the ammonia compressor and the refrigeration system. These case studies demonstrate the value these lubricants provide in reducing maintenance costs, extending equipment life and solving problems.
High Side Piping II
Author: Rex Brown

During the past 15 years there have been numerous papers and presentations regarding condenser piping, thermosyphon oil cooling piping and non-condensable purging piping. IIAR members worked diligently to produce the new piping handbook that describes and illustrates a recommended piping method; however, there are many existing systems and some new systems that do not utilize these recommendations. This paper explains the engineering principles involved and, more importantly, how the different piping methods can and do affect the system performance. 
Refrigeration Systems in Supermarkets with Utilization Of Ammonia
Author: Alexandre Presotto Jr. and Carlos Guilherme Suffert

This article describes the operation of refrigeration systems in supermarkets utilizing ammonia as a primary refrigerant and an intermediary fluid for the distribution of “cold” into the display counters and the cooling chambers. The article outlines the technical and economical advantages and disadvantages compared with traditional R-22 direct expansion installations. These ammonia installations were initially designed to reduce the amount of frigorigenous fluid in the installation. With the careful elaboration of ventilation systems in the machine room, the use of ammonia has become possible. An ammonia system is now a technically and economically feasible alternative for supermarkets systems that use halogenous gases. Based on several installations operating in Brazil, this article discusses the evolution of ammonia installation, which eliminates defrosting routines in medium temperature circuits. The main objective in designing these ammonia installations is to maintain proper product conditioning in extremely stable, low temperature circuits with energy performance similar to a direct expansion system.
Stress Corrosion Cracking of Steels in Ammonia
Author: Vernon C. Alexander and F. Michael Laucks

The first indication that ammonia could cause stress corrosion cracking came as a result of the development of cracks and leaks in carbon steel vessels in agricultural ammonia service. Investigation of failed tanks showed they had been properly (ASME Code) constructed. The heads were either deep drawn or cold formed. Most of the failures occurred either in the welds or in the heat-affected zones adjacent to welds. Metallurgical examination of failed vessels revealed numerous fine cracks on their interior surfaces, principally in the heads near the head to shell seam weld. These characteristics were typical of stress corrosion cracking and indicated that residual stresses were contributing to the cracking. In 1954, a research committee was formed by the Agricultural Ammonia Institute (AAI) to determine the cause of and methods for preventing cracking of vessels in agricultural ammonia service.