2002 IIAR Technical Papers
   Kansas City, MO
  24th Annual Meeting

CO2/NH3 Refrigeration Replaces R-22 in Large Freeze-Drying Plant
Author: Adrian Page

CO2/NH3 Refrigeration Replaces R-22 in Large Freeze-Drying Plant (2002)-Nestle UK owned a relatively large, complex, low-temperature refrigeration plant that was tightly integrated into its freeze-drying process. The existing plant operated on R-22 and some system components were more than 35 years old. After considering the plant's relative age, current operating costs, and the undesirable environmental nature of its refrigerant, Nestle decided to replace the plant. After a detailed examination of the options, the company concluded that the best solution was a CO2/ammonia cascade system. The company conducted a pilot test with a 100-kW, -54°C (about 30 tons at -65F unit commissioned at the end of 1998. After successful operation of the pilot, the plant was built and began taking load off the R-22 system in early 2001. The transfer was complete by mid-year. This paper outlines the history of the project and compares actual system operation and performance with the company's original expectations.
Control of Corrosion Basics: Corrosion Under Insulation 
Author: Patrick J. Dunn

This paper discusses basic corrosion principles and mitigation methods. Corrosion under insulation is a major problem, whether the pipe or another structure is buried or above ground. Three of the four requirements for metal corrosion to occur are present in every metal. The fourth element, an electrolyte, is present in wet thermal insulation. Using proper vapor barriers, coatings, insulation products, installation techniques, and  maintenance can all help control corrosion problems in piping.
Sizing and Design of Gravity Liquid Separators in Industrial Refrigeration 
Author: Bent Wiencke

Various "rule of thumb" methods have been developed for sizing gravity liquid separators for ammonia andother common refrigerants over the years. However, a clear systematic approach or an agreeable standard has not been established within the industrial refrigeration industry. For commonly used refrigerants such as ammonia, the installed base separators can be used as a benchmark for sizing separators. However, when using a less common refrigerant such as CO2 the designer faces new challenges. We present a systematic approach for sizing horizontal and vertical gravity liquid separators  for industrial refrigeration applications. To compute separation velocities and separation distances , a theoretical model is presented and supported by empirical data. Criteria and formulas for estimating the surge, ballast, and pump head volume are given to estimate the required liquid volume for storage. In addition, the phenomenon of liquid swelling and foaming is foaming is explained, along with the related considerations. We conclude with an example for sizing a separator for a typical industrial application. The differences between using NH3 and CO2 as refrigerants are highlighted, with emphasis on the separator, the pump supply lines, suction riser, wet return lines, dry suction lines, and pump sizing.
Over pressurized Systems Components, Hydrostatic Expansion, and Hydraulic Shock 
Author: Richard B. Thomas, P.E. 

Hydraulic shock or liquid hammer results when liquid moving at velocity through a pipe is suddenly stooped, creating very high pressure. An IIAR Bulletin and previous IIAR technical papers have provided insight into the mechanism causing condensation induced shock (CIS) with some suggested solution and precautions. Based recent experiences with CIS, this is a much larger problem than originally perceived. Serious failures apparently caused by CIS  have had large economic losses. The author has witnessed several instances of repeated CIS in ammonia systems where the engineers and or/ or operators did not seem to understand the cause or solution. Based on these recent experiences, design details to reduce or eliminate the risk of CIS have been developed. Some of the modifications made that have eliminated CIS are described here.  
Food Freezing Times and Heat Transfer Coefficients
Author: Bryan R. Becker, Ph.D., P.E. and Brian A. Fricke, Ph.D.

Freezing food is one of the most significant applications of refrigeration. Proper design of refrigeration equipment requires good knowledge of the surface-heat transfer coefficient for the freezing operation. This paper describes the thermodynamic of food freezing and reviews basic freezing-time estimation methods. It also describes a study to resolve deficiencies in heat transfer coefficient data for food freezing processes. Using actual freezing curves and transfer-heat data, a unique iterative algorithm was developed to estimate the surface- heat transfer coefficients of foods based  on their freezing curves. Making use of this algorithm, heat transfer coefficients for various food items were calculated fro the freezing curves collected during an industry survey. The algorithm described in this paper was developed and used in recent ASHRAE research project to generate over 800 heat transfer coefficients that will appear I future additions of the ASHRAE Handbook. These heat transfer coefficients can then be used with the freezing-time estimation methods to achieve efficient design of food freezing equipment.  
Energy Cost... Are Changing Refrigeration Design 
Author: Walter Gameiro

Rising fuel cost are having an impact on the economy of the United States and on the rest of the world. As prices per kilowatt-hour of electricity continue to go up, refrigeration end users must compensate by charging higher prices or reducing profit margins. This papers demonstrates how improvements to a poorly designed ammonia freezer saved 65% in utility cost in the refrigeration system alone. All features of refrigerated warehouses that have an impact on energy use are analyzed. the paper includes basic guidelines on how to design a state-of-the-art energy efficient refrigeration plant in general and a refrigerated warehouse in particular.
Shedding a New Light on Microbial Control in Air Handling Systems
Author: Tom Heisler and Bruce Paulson

All of the earth's inhabitants depend heavily on the restorative and regenerative properties of the sun's rays, particularly the ultraviolet (UV) spectrum and especially the C band (UVC). While a certain amount of UVC exposure is necessary for life, excess UVC will also kill microorganisms. This property of UVC has been successfully practiced for more than 65 years to disinfect reasonably still room air surfaces. With more awareness of poor indoor air quality (IAQ) and food safety issues, increasing focus in turning to UVC use, but now the new HVAC and refrigeration quality lamps. These new lamps can kill the molds and bacteria that grow on coils and in drain pans and the microbes that circulate in the air (e.g., bacteria, viruses, and other pathogenic germs).these lamps can also be used as part of a maintenance program to restore a cooling coil to its original system efficiency.
Successful  Integration of Industrial refrigeration Plants and Process Heating Plants into On-Site Generation Systems
Author: Chris Hastings, P.E.

Rising utility costs and continuing threats of power shortages have caused many facilities to take a fresh look at the applicability of on-site generation tot their facility. With steady year round requirements for refrigeration, in also in some cases process heating, many industrial facilities make great candidates for on-site generation. Current and future utility loads, permitting requirements electric utility interconnection, fuel availability, and the optimal plant size and equipment configuration are all issues which vary from site but can have a significant on the impact on the economics and viability of these projects. this paper will present some of the keys to effectively developing on-site generation projects and integrating them into existing refrigeration plants.    
What the Heck Do I Do With My Relief Valves?
Author: Lane S. Bonebrake  

Recent changes in design standards and other industry guidelines have left end users and engineers confused about maintaining relief systems. The ASHRAE-15 and IIAR-2 standards now outline different requirements for relief discharge lines. IIAR's new recommendations for periodic replacement of safety relief valves have been misinterpreted by users and regulatory agencies. This paper provides an up-to-date briefing on relief design and maintenance, including concrete recommendations, and an outlook for facilities and design engineers.   
Requalification and Continued Service Evaluation of refrigerant Pressure Vessels, Containers and Heat Exchangers 
Author: Brian Markey

For safety reasons, when activating pressure vessels originally designed for refrigerant services in new applications, it is important to recertify them properly. this paper focuses on pressure vessels such receivers, separators, evaporators, and condensers rated by any of the following recognized organizations: CRN, ASME, or API. Emphasis is placed on the specific requirements for "R Stamp" vessel certification. Significant care and attention to detail are required to ensure continued safe operation of repaired pressure vessels and containers. Non-destructive tests and repair procedures are addressed, in addition to requirements for removal from service with guidance from the applicable regulations. Inspection procedures for plant maintenance organization concerning ammonia refrigeration equipment are also addressed.      
Single-Stage versus Two-Stage Efficiency Consideration  
Author: Henry B. Bonar II

Over the years, industry engineering have often discussed the relative merits of two-stage versus single stage central ammonia refrigeration systems. To this day, however, pertinent considerations continue to be overlooked. Engineers should review the entire system using such tools as Mollier diagrams to determine which of the relevant factors will significantly influence a particular compressor selection. Principle among these considerations are the type of compressor, system operating conditions, condenser operating parameters and efficiency, and vessel size and types. This paper illustrates how these factors can affect engineering decisions made in designing or expanding refrigeration systems.