1996 IIAR Technical Papers
  Atlanta, GA
 18th Annual Meeting

Ammonia Absorption Refrigeration
Author: George Briley

A unique approach to combining classic ammonia absorption and a gas engine generating system to reduce energy costs in a cold storage warehouse will be discussed. But first, the classic ammonia absorption system will be described, including how it works. There are a number of advantages to using ammonia absorption systems, including: low maintenance costs, high reliability, minimal installation space, quiet, automatic control, no damage from overloads, and high efficiency and flexibility.
Refrigeration with Waste Heat
Author: Donald Erickson

Converting waste heat to valuable refrigeration with an absorption refrigeration cycle has long been recognized as a viable technical procedure. However perceptions have formed which currently limit its use. These perceptions are: that the required waste heat temperatures are too high; that the useful refrigeration produced is too little; and that the cost is too high. Those perceptions were true for the absorption technology of yesteryear, but they no longer apply to the modern technology now emerging. New absorption cycles have greatly increased performance and/or reduced the required driving temperatures. And applications of modern heat and mass transfer techniques are dramatically reducing the cost of absorption equipment. As a case in point, this paper describes a new "double-lift" absorption cycle now in operation which uses 176°F or lower engine jacket cooling water to power a ten ton per day flake icemaker.
Technical Aspects of Recirculated Ammonia
Author: Henry Bonar II

Over the last 20 years, ammonia refrigeration systems have gone through significant advances in safety and reliability. But we haven’t reached perfection, despite the very best efforts of many different engineers, contractors, manufacturers and owners. If you were looking for a subtitle for this presentation, it would be “How to avoid the pitfalls and potholes of recirculated ammonia systems”.
Sizing Screw Compressor Unit Safety Relief Valves per ANSI/ASHRAE 15-1994
Author: Rudy Stegmann

The 1994 safety code satisfies the desires of those who must size relief devices for screw compressor units. It specifies the compressor flow criteria and permits reduction in the total flow when the compressor utilizes capacity control (unloading) at high pressure demand, and it also protects the oil separator vessel by limiting the maximum pressure rise during a release. Those involved with the design and protection of screw compressor units should study ANSI/ASHRAE 15-1994 and make certain that your units are in compliance. 
The Influence of Vapor Pressure in the Condensing Process of the Ammonia Refrigeration Cycle
Author: Milton Garland

Any condensing structure where the refrigerant is internal of the heat exchange pipe or tubing must have the assistance of gravity and have correct tube diameter and number of tubes wide sufficient to maintain an internal heat exchange surface for vapor cooling, with no less than 80% of the internal heat exchange perimeter available for that vapor cooling. The pipe or tube length should also be of sufficient length to provide an outgoing liquid temperature of no more than 5F above that of the coolant in a counterflow arrangement. The liquid temperature in the receiver must be maintained at the average liquid temperature from the condenser by providing vent piping to carry any vapor caused by liquid heating into the area of lowest vapor pressure, which is the outlet from any one of the condensers.
Energy Efficiency Case Studies in Ammonia Refrigeration: Heat Pumps, Head Pressure Reduction and Optimized Control Systems
Author: Marcus Wilcox

This paper presents the theoretical underpinnings and practical application of several state-of-the-art energy efficiency opportunities in industrial ammonia refrigeration systems. These efficiency opportunities include head pressure reduction, heat pumps and optimized control. Brief technical discussions will identify/provide energy-related incentives to implement these technologies. Several case studies will present "real world" applications, with unique solutions to energy inefficiencies and related potential roadblocks. In addition, discussion will be devoted to ensuring optimum control strategies to maximize energy savings.
Troubleshooting Revelations
Author: Vernon Alexander

This paper deals with the first phase of determining the cause of a problem and, depending upon the circumstances, its correction. No attempt has been made to become involved with the engineering aspects; in many cases they are obvious. Though an occasional observation or suggestion is made to emphasize or illustrate a point, this is not intended as a workshop lesson in design. This paper will describe problems the author has encountered in troubleshooting industrial refrigeration systems, including: Accumulator/ Pump Receivers, Fan Coil Evaporators, Piping Ammonia Pumps, Oil and It’s Removal, Shock & Pressure Failures, Operating Personnel, System Startup, Safety Relief Valves, and Evaporative Condenser Piping.
Flammability Limits of Ammonia-Air Mixtures
Author:  Donald L. Fenton, Ph.D, Kirby S. Chapman, Randy D. Kelley & Ayaz S. Kahn

The information reported here results from a recently completed ASHRAE sponsored research project, RP-682, called "Combustion of Ammonia, With and Without Oil." In this project, literature concerning ammonia combustion was reviewed, experiments were performed measuring the flammability of ammonia-air mixtures with and without lubricating oil, and a specially fabricated ammonia oxidizer was operated under a wide variety of conditions where the operation and exhaust emissions were monitored. The results of this project are reported fully in ASHRAE technical papers and the project's final report.
A Path to Compliance for Process Safety Management and Accidental Release Prevention
Author: Rich Antoff

This paper draws upon the experience gained from implementing Delaware's EHS Regulation. Delaware's Extremely Hazardous Substances (EHS) Regulation was promulgated in September 1989; facilities were to come into compliance with the accident prevention program by September 1990 and complete their initial Process Hazard Reviews by September 1991.
The Regulator's Use of the Worst-Case Scenario
Author: Neil Mulvey, James Cibelli, and Deborah Reuther

The requirements of the USEPA’s Risk Management Program (RMP) regulations (40 CFR Part 68) to perform worst-case scenario analysis of potential acute accidental releases of listed regulated substances will make mandatory everywhere an effort that has been occurring in various states throughout the country. The USEPA’s RMP regulations will require covered ammonia refrigeration facilities to perform worst-case consequence assessments of catastrophic accidental releases. Consequence assessment information will, for the first time, be publicly available. While there has been considerable discussion on the definition of “worst-case” as it relates to ammonia refrigeration systems, and the high degree of subjectivity in performing such analyses, there has been relatively little discussion on how this information will be used. For several years, New Jersey, California, and Delaware have required dispersion and consequence analysis as part of their risk management programs. Ammonia refrigeration facilities in these states have been conducting and reporting to state and local agencies the results of off-site consequence assessments. This paper will review activities and programs in these states and evaluate the use of this data for risk management, emergency response planning, and public information inquiries. The paper will also address the planned use of the data to be generated by the USEPA’s RMP regulation; it will also offer recommended uses of this information as it relates to ammonia refrigeration, as well as potential misuses of the data.
Identification and Modeling of Worst-Case Scenarios for Ammonia Refrigeration Systems
Author: Geoffiey Kaiser

In its forthcoming Risk Management Program (RMP), 40 CFR Part 68, the United States Environmental Protection Agency (EPA) will require worst-case scenario modeling for facilities containing over 10,000 pounds of anhydrous ammonia. Many ammonia refrigeration systems will be affected. This paper discusses the worst-case scenario, which for most refrigeration facilities will most likely be a severe leak from or in the vicinity of the high pressure receiver. The atmospheric dispersion modeling of this scenario is also discussed. In addition, there is a short review of the choice and modeling of ''more likely" or "alternate" scenarios. The work discussed is intended to be general enough to apply to most refrigeration facilities, although it is recognized that there will be exceptions that will need to be considered on a case-by-case basis.
Technical Aspects of Semi-Welded Plate Heat Exchangers when used as Evaporators and Condensers
Author: Douglas Villemain, Keith Gifford, James Mitchell, and Mats Stromblad

A brief overview of semi-welded plate heat exchangers (PHEs) is presented, including their design, operation, and construction. Additionally, this paper addresses some common technical issues when considering semi-welded PHEs for industrial refrigeration applications. Unless industrial refrigeration systems are properly designed, maldistribution of liquid refrigerant can occur in plate evaporators. The cause of refrigerant maldistribution and steps that can be taken to minimize the occurrence will be addressed. This paper will discuss issues pertaining to heat transfer coefficients, approach temperatures, pressure drops and liquid refrigerant feeds. Additionally, concerns regarding freezing of a plate evaporator and the resulting consequences will be addressed.
The Design and Operational Characteristics of Ammonia Spray Evaporators
Author: Zahid Ayub

Ammonia has excellent heat transfer and flow characteristics and has zero ODF (ozone depletion factor). However, due to the toxicity of this refrigerant, it has become important to devise heat transfer systems that hold low refrigerant charge and have superior heat transfer performance. One such heat transfer component is the spray evaporator. This paper describes the design and operational characteristics of ammonia spray evaporators.
Applications for Ammonia Cooled Liquid Dessicant Air Conditioning in the Food and Beverage Industries
Author: W.C. Griffiths

This paper provides an introduction to the liquid desiccant air-conditioning process and equipment. In addition, several food and beverage-related process air conditioning applications using ammonia refrigeration will be described.
Ammonia Screw Chiller for Air Conditioning in a College Central Plant
Author: Mike Whitcomb

This paper describes the use of ammonia as the refrigerant on the Rockville, Germantown and Takoma Park campuses of Montgomery College in Montgomery County, Maryland. The installations are unique since the central plants are located in the basements of classroom buildings. The Rockville Campus installation is a renovation of an existing central plant located in a 30 year old building and has been operational for three cooling seasons. The Germantown Campus central plant is located in a building currently under construction and is scheduled to be completed in January 1996. The Takoma Park Campus central plant is to be located in a basement storage area of a classroom building and will support a planned expansion of the campus. It is currently being reviewed for funding and plans are to prepare a design in the Summer of 1996.This paper presents the design considerations, safety systems and operating experience of these systems.