1991 IIAR Technical Papers
   San Francisco, CA  
  13th Annual Meeting

Ammonia Creates the Perfect Environment
Author: Randy Kastello

All of us gathered here are so-called experts on Ammonia Refrigeration. Otherwise, we wouldn't be members of IIAR. What most of us are NOT, however, are experts on Ammonia Air Conditioning. This is still a rather unexplored, untested market, although some companies have previously dabbled in it. But, with the CFC controversy looming around us, ammonia air conditioning applications are becoming more prevalent - as many of you can attest to. During the last year or so our Company has sold several Ammonia Water Chillers, some fairly standard, some quite unique. One of the more unique Air Conditioning applications that our Company recently got involved with is also one of the most interesting Air Conditioning jobs ever requested. It involves cooling a miniature earth.
Analysis of Engine Powered Refrigeration with Heat Recovery in Industrial Refrigeration Plants
Author: Ronald F. Amberger, P.E., John A. DeFrees, P.E. and Ernest Wichert

This project was initiated to investigate applications of gas energy refrigeration technologies at Honeywell Farms, a major dairy located in Jamaica, New York. The primary goal of the project was to determine if certain gas energy technologies could be utilized for economic advantage under current production loads and increases of up to 100 percent. An approach based extensively on computer modeling techniques was adopted in pursuit of this goal. Overall, sixteen combinations of new and existing equipment were examined. The performance of the existing facilities was modeled in order to establish a baseline for comparative purposes and as verification of the modeling technique.
Limited Inventory Ammonia Falling Film Spray Evaporator
Author: Zahid H. Ayub, Ph.D., P.E. and Stephen K. Knewitz

The purpose of this paper is to present ammonia as a prominent refrigerant of the future for spray evaporators. In the past, limited work has been performed by researchers on falling film spray evaporators. The works of several researchers (Conti, 1978; Sabin and Poppendiek, 1978: Hillis, Lorenz, Yung, and Sather, 1979;and Fricke and Czikk, 1979) are prominent in the open literature. This paper will look into the work of these researchers, present the important aspects of their studies, and discuss the potential of enhanced surfaces.
Energy Efficiency Comparison of Advanced Ammonia Heat-Exchanger Types
Author: C. Panchal and T. Rabas

This paper evaluates the energy savings or COP improvements that can be obtained through the use of enhanced tubes and advanced heat-exchanger types for some ammonia refrigeration applications. Current practice for process liquid chilling is to use plain or unenhanced heat-exchanger tubing in conventional shell-and-tube heat exchangers for both the evaporator and condensers. Because of environmental concerns, some of the future air chilling and air conditioning replacement systems may be the indirect type which require ammonia-liquid heat exchangers for an intermediate heat transfer fluid. The COP penalty will be very critical for these applications. In many cases the existence of cooling-tower systems for heat rejection will lead to the reuse of ammonia systems, making ammonia-water condensers an attractive alternate. It will be demonstrated that the energy efficiency can be improved with advanced heat-exchanger concepts for these refrigeration systems involving the chilling of a liquid and/or the rejection of heat to a liquid with ammonia as the refrigerant.
Air Conditioning with Ammonia "The Perfect Solution"
Author: Steven J. Toth

Most of you are at least somewhat familiar with the CFC issue, the Montreal Protocol. The phasing out of CFC refrigerants by the year of 2000. This paper will not repeat the discussions concerning the effect of CFC refrigerants. It has been done many times by many others in the past 2-3 years. Since most of the air conditioning was done with CFC refrigerants in the U.S., the scramble began for replacement refrigerants. You heard, no doubt, about new refrigerants, some of which eat up gaskets, copper windings, etc. For those of you who were raised on ammonia, the natural or "Perfect Solution" is to use ammonia, one of the most efficient refrigerants for air conditioning. While most of you are familiar with ammonia refrigeration, some of you may not have experience with air conditioning applications. Although it is not quite a "piece of cake", it is not very exotic either.
Evaluation of Water as an Ammonia Trap
Author: Donald L. Fenton, Amy F. Noeth and Robert L. Gorton

ANSI/ASHRAE Standard 15-1989 recommends a procedure for trapping ammonia when released from a refrigeration system. Experiments were conducted where ammonia was released to a receiver vessel resulting in the Standard 15 (ASHRAE 1989) suggested ratio of water-to-ammonia. Standing water was measured to absorb 90% of the ammonia vapor released. However, standing water was observed to absorb 100% of the ammonia liquid released. Use of a water spray inside the receiver vessel at the Standard 15 (ASHRAE 1989) recommended water-to-ammonia ratio absorbed approximately 85% of the ammonia vapor released.
Salt Brine Cooling Systems in the Cheese Industry
Author: Robert S. Burdick

Salt brine systems are common in many cheese plants in Wisconsin. The cooling systems for these various applications involve the identification of loads not usually discussed in most tests or handbooks. This paper describes how these loads can be calculated and how refrigeration systems and equipment are used and applied in these cheese plants.
The Development of Gas Pressure Recirculation Systems - An American Phenomenon
Author: James D. Wright, P.E.

The concept of using high pressure refrigerant gas to transfer and recirculate liquid refrigerant in a refrigeration system was pioneered and developed here in America by two inventive genius friends; Harry A. Phillips and Jack Watkins. Subsequent work by Bill Richards, Herb Rosen, Bob Ross, and Rowe Bansch has served to develop and further refine these concepts into practical and efficient refrigeration system designs that are applied today in the industry around the world. A review of these developments and their evolution in time provide great insight into how the systems work and the practical applications they may serve. It also gives honor to the creativity of these men in our industry, some of whom are with us here today.
Compoud Screw Compressors: Low Temperature Applications
Author: Moshe Y. Dreksler, P.E.

The positive displacement two-stage compound screw compressor is designed to operate in reliable manner with R-717, R-22 and similar high pressure refrigerants. It is well suited for typical low temperature industrial plant requirements, e.g. product freezing, freezer storage, process cooling and liquefication, freeze drying and similar applications of variable low temperature operating conditions. The compound units with single motor drive, simple oil management and continuous capacity control of each stage, provides for a compact packaged unit configuration, with low power consumption especially at part load. The complete unit is monitored from a single control panel. Preliminary selection of a compound unit for plant low temperature refrigeration requirements is readily performed using the basic performance curves. Multipliers are used to adjust for any subcooling, side loading and types of oil cooling. Accordingly, the performance parameters can be visually related to plant operational modes, yielding more pertinent computer input information and more meaningful computer print outs for better analytical compound selection. Available compound screw computer performance programs allow for the selection of the best compound unit size for the plant's various operating parameters and with lowest attainable power consumption.
New Generation of Screw Compressors
Author: Charlie Klockner

All of you are at least partially familiar with twin screw compressors. Some of you are even partially familiar with single screw compressors. Only a couple of you are completely familiar with single screw compressors. So we can all get off on the same foot, a quick review of screw compressors, in general, may be in order. Than we'll talk briefly about some of the differences between single and twin screws, and, finally, discuss the latest developments of the single screw, making it a viable industrial machine.
Enhancement of Refrigeration Efficiency by a Modified Vapor Compression Cycle
Author: Dr. Uzi Mann and Dr. Ram Lavie

This paper describes a modification of vapor compression cycles with a novel Heat-Mass-Exchange (HME) technique. The HME unit reduces irreversibilities by utilizing the heat generated in the compressor to pump a portion of the refrigerant. A power savings of 4.2% can be realized on an industrial-size ammonia refrigeration system. The technique also allows the utilization of low grade heat sources (say, at 100°C) to supply a portion of the required thermodynamic work. Calculations indicate that by utilizing such energy sources energy savings of 20 to 30% can be realized. Theoretical and technical considerations of HME-enhanced vapor compression cycle are discussed and two specific examples are provided.
Pressure Relief Consideration for Refrigeration Equipment
Author: Joseph C. Leung

Pressure relief sizing for refrigeration equipment is considered in this paper. In particular the ASHRAE fire sizing formula (ASHRAE, 1978) is critically examined and comparisons are made with methods employed in other engineering institutes. The traditional sizing approach based on vapor relief is re-examined in light of the recent findings from the DIERS (Design Institute for Emergency Relief Systems) work. The occurrence of two-phase discharges during relief may result in significant over pressurization of the refrigeration equipment. The purpose of this paper is to suggest a methodology adequate for most designs and which has been verified with available experimental data.
Pressure Drop in Two-Phase Flow
Author: Peter Chr. Jacobsen

In the early 1980s, our firm searched the market for a computer program designed to handle two-phase flow of refrigerants. Finding none, we developed our own program which could be used to size refrigerant piping as well as to calculate the theoretical pressure drop in proposed or existing systems. This paper will describe our approach and theory we used for the two-phase flow calculations. It will also point out how we tried to make it easy to analyze a complete system in one round.
Fabric Duct Systems for Refrigerated Environments
Author: Dave Withee

Fabric duct systems (with appropriate U.S.D.A. approvals) have the capability of: Increasing productivity by eliminating wind-chill causing drafts; Decreasing air distribution costs by replacing the need for perforated spiral pipe, metal duct systems, or additional low-velocity cooling units; Decreasing cleaning and maintenance costs of air distribution systems; Improving product quality by eliminating moisture absorbing drafts and temperature stratification; and Improving air quality by providing secondary filtering of particulates that avoid primary filtering systems.
Improved Freezer Operation using Secondary Circulating Methods
Author: W.V. Richards

The popularity of central ammonia liquid pumping systems in freezing plants combined with the development of very tall storage rooms and process freezers has resulted in impaired capacities due to pressure drop in the wet return risers. The ideal layout is to locate the piping below the coils so that the overfeed liquid will have the benefit of gravity flow. But in many cases the evaporators are below the piping or the coils are stacked in a blast freezer and the piping is near the ceiling or on the roof. Locating valve groups outside, on the roof, is a safety precaution that should be encouraged as this reduces the potential for leaks within process areas. However, this practice has reduced the efficiency of central circulating systems. Several methods that have been successfully used for reducing these losses are illustrated in this paper.
Water Treatment for Evaporative Condensers
Author: Michael D. Sanders

The purpose of this paper is to provide a basic understanding of the role water treatment plays in the evaporative condenser systems. We will discuss specific aspects of scale, corrosion and biological control. Also, methods of simplifying water treatment feed and control of multiple evaporative condenser systems will be discussed.
Suitability of Pipe Materials for use in Ammonia Refrigeration Systems
Author: Richard C. Bond

This paper is presented to cover piping applications for temperatures of -40F degrees and higher. It is understood that special design considerations may be required at temperatures below -40F. Refrigeration piping at these lower temperatures is a special subject, probably worthy of another paper, but it is not a part of this presentation.
Emergency Response Operations
Author: Robert L. Harmon

To respond to emergencies involving chemical spills or releases requires that employees responding have adequate personal protective equipment and training prior to responding. This is not only the law, it is also the responsibility of the employer as well. The equipment must be selected based on the hazard. This training should include a basic grounding in the understanding of hazardous chemicals found in the workplace. The "specialist" employees must also have a working knowledge, not only of their own emergency action plans, but of the plans of the local community as well as state and federal requirements. This will insure that all efforts are coordinated to insure favorable results. A great deal of thought must go into the training program to guarantee that all the objectives of the OSHA requirements are met.
Ammonia Refrigeration: Are We Doing it Right? An End Users Point of View!
Author: Richard H. Stamm

The following is presented as constructive criticism of the ammonia refrigeration industry from the end users point of view. There are a lot of suggestions for changes in the way the ammonia refrigeration industry does business. The following is offered with the hope that it will create discussion, arguments, turmoil but will eventually result in logical, intelligent changes that will benefit the end user and ultimately the entire industry.
Advanced Microprocessor Control for Refrigeration Systems
Author: Jim Conant

Recently, with the advent of advances in both hardware and software, microprocessor control technology has been extended and applied to refrigeration system control. However, the degree of control capability and the resulting operating success of these systems has proven to be directly proportional to the sophistication and extensibility of the microprocessor control system. What follows is a discussion of these recent microprocessor control advances, their applications in industrial refrigeration, and the beneficial features they deliver.