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1984 IIAR Technical papers
San Francisco, CA
6th Annual Meeting
Ammonia Shut-Off Valves: An Update
Author: Charles C. Hanse, III
During the past 10 years, there has been increasing usage of alternative designs of manual shut-off valves for ammonia refrigeration systems. Whereas cast iron threaded end and flanged globe valves and angle valves had been the traditional norm, the demands for lower pressure drop, lighter weight, lower cost, and faster availability have resulted in the increased usage of designs which had already been popular in other industrial segments or other parts of the world. Each of the designs, old and new, have certain natural advantages and disadvantages, which this paper will explore in more detail. Consequently, each of the designs has its unique place, depending upon the demands of the various portions of each ammonia industrial refrigeration system. This paper is limited to consideration of simple manually operated valves which are normally fully open or closed. They are intended to permit or to stop fluid flow and pressure transmission between two parts of a refrigeration system.
Oil in Refrigeration Plants
Author: Vagn Villadsen and Fleming V. Boldvig
Failing or insufficient lubrication is a major cause of compressor break-downs. The lubrication may fail for a number of reasons, a. o. too much superheat of the suction gas, too high discharge gas temperature from too high compression ratio, too high refrigerant content in the oil, or too high oil temperature, e.g. due to failing compressor cooling. A considerable part of all break-downs could be avoided either by selecting a more suitable oil, by small improvements in plant lay-out, or by minor changes in operating conditions. Compressor lubrication is therefore an important subject, which, so far, has not been given the attention it deserves.
Practical Pipe Sizing for Refrigerant Vapor Lines
Author: William V. Richards
The usual piping charts offered by refrigeration associations or manufacturers list the pressure drop per 100 feet of length. These piping guides do not suggest what the proper pressure or temperature loss should be. They merely make it convenient to determine the pressure loss in a given system. A rational approach to sizing refrigerant vapor lines involves matching the cost of piping against the life cost of friction in the system. In a previous paper, a method of calculating the optimum flow rate was presented. A presentation of useful tables and charts based on this method applied to refrigerant vapor line sizing is the purpose of this paper.
Infiltration: A Load Calculation Guide
Author: Ronald A. Cole, P.E.
Infiltration loads present the most vexing problems to the refrigeration system designer, not the least of which is a means of determining their magnitude. The designer has had to rely on popular published data of questionable origin and dubious reliability or rules of thumb such as tons / door, developed empirically, likewise of debatable applicability. In the work statement for a proposed research project dealing with the subject of infiltration, it was suggested that approximately one half (1/2) of the total refrigeration energy consumption nationwide is due to infiltration air. This may or may not be an overstatement: but not with-standing, the problem is a significant one and worthy of additional attention. The intent of this paper is to present, from data already available in the literature, a rational method for estimating refrigeration load due to infiltration. It will present some mathematical as well as nomographic methods for quantifying infiltration loads that will provide some analytical flexibility, offer some suggested limits of reliability and suggest the need for additional research or perhaps expand the scope of currently proposed research.
Here Comes the Sun and 67% Energy Savings
Author: B. S. Schaeffer
One terminal distribution facility, constructed in Tampa, Florida in 1977, incorporates an imaginative application of that State's most abundant natural resource to significantly reduce annual operating cost. Using solar energy to heat the ammonia liquid has reduced the design usage of fossil fuels by sixty-seven percent. The terminal storage and distribution of liquid ammonia involves several important heat balances that should be of interest to the curious refrigeration engineer. Variations in the application and control of typical refrigeration components are used to maintain critical pressures, distribute vapor, remove heat gain, reduce liquid temperature, and, in the Tampa instance, increase liquid temperature for shipping over land.
Lubricant (Oil) Seperation
Author: George C. Briley
Properly managing the lubricant (oil) that is normally circulating within a refrigeration system employing helical screw compressors is the key to efficient plant operation. When the lubricant (oil) quantity in the evaporator(s) becomes excessive, lots of things happen -- most all of them are bad. With the latest developments in both lubricants and separation systems, lubricant carryover can be reduced to negligible quantities with minimal capital investment.
Maximizing Refrigeration Cycle thru Innovative Controls
Author: Bob Cantley
This paper is based on results obtained from an actual plant operation where operating design, control and parameters were changed to optimize operating, control and design parameters. The scope of this paper covers the operation effect seen in respect to condensers, piping changes, receiver, booster/compressor operation, purgers, and mechanical changes required to operate at 50 head pressure and hot gas defrost.
The Cost of Frost
Author: Marcia B. Coley
For several reasons the most difficult electrical utility loads to control in a meat processing plant are the carcass chill coolers. In the case of hog chill coolers, the hogs arrive in the chill cooler at an average temperature of 105°F directly from the kill floor after a thorough washing. The freshly slaughtered hogs must be chilled to an internal temperature of 38-40°F as quickly as possible under the proper conditions of temperature, humidity, and air movement to retard microorganism growth in the carcass itself. In accomplishing this, the loss of moisture from the hog carcass must be held to a minimum, and at the same time, the carcass must leave the cooler in a firm state suitable for efficient cutting and processing.
The Development of a Totally Automatic Multi-Point Non-Condensible Gas Purger
Author: John A. Yencho
With the ever increasing demand for more energy efficient refrigeration systems, manufacturers, contractors, systems designers and end users are re-evaluating each component to make improvements wherever possible. Purgers are an area where improvements are necessary. This paper suggests several ways to improve their operation.
Ammonia - History, Uses, Safe Handling
Author: G. E. Krueger
This paper covers the history, production, purity, transportation, industrial uses and safety of ammonia.
Hot Gas Defrost A One, A More, A Time
Author: Arthur P. Strong
It is convenient to think of a hot gas defrost system as if it were a steam heating system. There must be an adequate quantity of vapor, at a pressure high enough to force the vapor through the heat exchanger, and its condensate back into the return line. The condensing temperature must be warmer than whatever it is trying to heat. And, there must be a means of knowing when heating is required and when it is not required.
A Case Study of an Engine Room Controlled and Operated by Computer
Author: R . D. Watson
I am sure you are all familiar with the tremendous expansion of computer technology in markets such as toys, TV games, home computers, appliances, automotive, office products, etc. The computer has now found the refrigeration industry and this morning I will tell you about one of the first, if not the first, computer system dedicated to the control and operation of an engine room. The two key elements in this system are, of course, the microprocessor control panels on the screw compressor units and the desk top computer. In order to understand how this system functions, it is necessary to understand the individual capabilities of these elements and how they interact with each other. It is obvious that microprocessor technology has given our industry new dimensions of protection, observation, and control that simply have not been feasible before.
Piping Evaporative Condensers
Author: Wilson E. Bradley
Over the years there have been a number of articles written on this subject of piping evaporative condensers, and by now one would expect the piping practices to be pretty well understood. However, even today it is surprising how many jobs are poorly piped with resulting losses of efficiency and other operating problems. Actually because of a concern that there is still a significant amount of misunderstanding about the subject, the IIAR program chairman approached us to produce this paper. Really the principles involved in making a good evaporative condenser piping hookup are rather straight forward and only a few simple rules need to be followed. Most problems occur on larger, multiple unit installations and in particular when new condensers are added onto existing systems.