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1980 IIAR Technical Papers
Lake Buena Vista, FL
2nd Annual Meeting
Energy Cost Comparison: Cryogenics vs. Mechanical Freezing System
Author: George C. Briley
Capital savings of increasing energy efficiency in light of rising energy costs. Comparison of cryogenics and mechanical freezing systems. Cost and facility analysis of liquid carbon dioxide vs. liquid nitrogen mechanical systems. Physical properties of liquid carbon dioxide and liquid nitrogen. The difficulty of measuring shrink or dehydration. Cost comparison of the “cost to freeze” fried onion rings and hamburger patties with liquid carbon dioxide vs. liquid nitrogen mechanical systems. Idea of incorporating a two-stage ammonia system with a combination mechanical-cryogenic liquid carbon dioxide system.
Efficiency Considerations for Two Stage Systems
Author: Raymond P. Klinger
The paper presents some of the more common interstage configurations for two stage rotary screw compressor applications and relates the design choices to operating efficiency and power cost. To accomplish this, a nominal 110 ton system operating at -40°F/+10 F/96.2 F will be examined.
Operating Conditioners and Motor/Compressor Selections- Keys to Energy Savings in Refrigeration Systems
We all keep hearing the same old "song and dance" about operating conditions. "Keep your head pressure down, keep your suction temperature up, hold your superheat down, design for adequate subcooling, select compressors to match load and keep them loaded, use high efficiency motors and keep the power factor up" and so on and so on; but nobody stops to relate just what effect all of this really has on operating costs and how it relates to first cost. What we'd like to do is provide a few brief examples of the effect of operating conditions on energy consumptions, provide a few "rules of thumb" for future analysis and, hopefully, provide enough "food for thought" to consider energy along with purchase price the next time we design a refrigeration system.
Efficiency Measures in Ammonia Plants
As manufacturer of high-quality refrigeration compressors and equipment, naturally we are very concerned that our products should be put to the best use possible. Unfortunately (or luckily?), the manufacturer is not alone in the decision making, and a survey of a large number of actual installations will show that, generally, considerations concerning low first cost have dominated over considerations concerning low operating costs. A part of the explanation is of course that most of the plants in operation were installed before the so-called energy crisis was discovered. However, even recently installed plants, quite often have far too little or no consideration at all for low energy consumption. In the following we shall discuss some examples of too high energy consumption, and continue with compressor efficiencies and selection.
Energy Conservation Using Shell and Tube Condensers as Water Pre-Heaters
Outline of Required System Components: Refrigeration System, Water Usage, and New Equipment for Recovering Waste Heat; Heat Exchanger: Construction, Sizing – Use Energy Law, and Final Sizing; Installing the Heat Exchanger: Series vs. Parallel Operation with Condensers, Height and Piping Pitch for Condensate, Temperature Measurement and Allowance, and Equipment Protection and Control; Pay-Back Estimation: Straight-Line Method and Total Savings Estimation; Other Applications: Recirculation to Reach Higher Temperatures, Comfort Heating, System Defrost and Process Water Heating. Sample Problem Titles. Useful Formulas. Sample Survey Form for Heat Reclaim System.
Ammonia Truly An International Refrigerant- Yes or No?
There are many factors that influence the decisions that are made when the refrigerant, and hence, refrigeration equipment is being decided upon for a new industrial plant, and the factors influencing this decision vary throughout the world. This analysis has been limited to North America and Europe as there are some problems in obtaining reliable data from Japan because of their very heavily orientated export business and their heavily protected national business, and information from eastern Europe, Russia and China is difficult to obtain. But as a large percentage of the Japanese equipment is exported to USA, Europe, and the third world countries, it is reasonable to assume that the trends will follow the same pattern. And with the advance in petrochemical plants and a development of a consumer industry in the Eastern Bloc and communist countries could assume that similar trends may follow behind the western world trends. A review of this paper shows that Ammonia as an industrial refrigerant is declining in use internationally, and this decline must be attributed somewhat to the constraints imposed on its use along with a reduction in the ability and confidence to apply ammonia as an efficient, safe refrigerant.
Should We Consider Using an Energy Saving Rooftop System on Our New Perishable Warehouse?
Author: Richard Stamm, P.E.
I was almost ready to fight when my friend, client, and owner of a number of refrigerated buildings asked this question. I knew he would be better off with a central refrigeration system, but that was just a gut feeling. I didn't know; How Much Better Off? Why?...and as it turned out, we learned a lot, proving some things we expected, and proving some things we had "known" were false.
Nothing is Forever: Research Shows How Conventionally- and Retortable Pouch-Canned Products Benefit from Refrigerated Storage
It is becoming clear that the big important development in food processing, intended to answer problems of quality retention and energy consumption, is the retortable pouch. Because of the reduced requirement for heat sterilization, it has been alleged that food "canned" in a pouch is equal in quality to frozen food and that it does not require refrigeration, but is shelf stable. We acknowledged that there is some improvement in the quality of foods packed in a pouch initially; however, we have also demonstrated that vegetables, and probably many other commodities regardless of how they are canned and packaged are not the equivalent in quality to frozen products, with possible exception of "stew-type" foods. Furthermore we have indicated that the pouch-packed products require refrigerated storage even more than conventionally canned foods to maintain whatever quality advantage they do have over the conventionally canned equivalent.
A Balanced View of Reciprocating and Screw Compressor Efficiencies
The company has been engaged in reciprocating compressor design since the turn of the century and in double rotor screw compressor design since 1969. During the last five years a thorough test programme has been carried out in co-operation with Norges Tekniske Hogskole, University of Trondheim, on our reciprocating compressor design to determine the exact influence of the various design parameters on compressor efficiency. In particular the optimal design of the ring plate type suction and discharge valves has been studied. The paper will report on the variations in volumetric and isentropic efficiencies both for R22 and R717, in relation to speed, length of stroke, valve spring design, compression ratio, etc. The results obtained with the reciprocating compressor are compared with those for the double rotor screw compressor, based on experience from more than 1000 units supplied, and on various results obtained on the company's behalf by the licenser's laboratory. The differences are explained, and the conclusion is substantiated that both types of positive displacement compressors have their own merits, and that they complement each other to the extent that they may often be combined in one plant to obtain the most energy efficient installation under variable operating conditions.
Mechanical Refrigeration Standards - How Standard Are They?
A comparison is offered, a critique of the conflicting requirements that exist today between typical mechanical, safety and performance codes. Recent interference by government agencies and the courts into the writing and interpretation of standards should alert engineers to the need of demonstrating to the public the value of our current voluntary standards. A wider participation by various interests representing both the public and industry in writing and reviewing standards is urgently recommended. Included are reference lists of pertinent standards and standard writing organizations followed by a description of how voluntary standards are generated, their benefits, their impact on government legislation, and a discussion of some difficulties that will result if we let government assume the standards writing role. Tables of comparison of the typical standards applied to ammonia water cooled refrigeration plants are shown for equipment specification, design specifications, and for installation and operation requirements. The discussion points out the need for resolving differences in definition of terms, in the treatment of machinery room and system requirements for strength and leak testing, ventilation, and emergency fire relief protection. The contents should prove useful to those people who design, install, or operate refrigeration plants.
Heat Recovery from Screw Compressor Oil Cooling
Industrial refrigeration screw compressors can be a valuable source of readily recoverable heat. Some of this heat may be available at different temperature levels and in different places in the system compared with other compressor types as a result of the oil flooding feature used on screw compressors.
An Economics Approach to Energy Conservation
Author: Bruce S. Schaeffer
The information herein is composed as a real world approach to the economics of energy management for conservation. No matter how patriotic a business entity may be, the true test of energy management in industry is based on economics. Thus, this writing deals with energy management concepts in the terms of payback, R. 0. I., and investment cost analysis.