2015 IIAR Technical Papers
San Diego, CA
37th Annual Meeting

In the years since the Montreal Protocol went into effect in 1989, the global refrigeration and air conditioning industry has met the challenge of phasing out ozone depleting chemicals and adapted well to achieving increasing efficiency for their equipment using synthetic hydrofluorocarbons (HFCs) in most common applications. In large industrial applications, ammonia has become the standard refrigerant of choice, even though HFCs are used in some installations. In recent years, the alarming growth and emissions of HFCs into atmosphere has caused concern that, if left unchecked, these HFCs could become a major contributor to global warming gases in the atmosphere. Starting with some European countries, and followed by Australia and eventually the rest of Europe, governments have started taking action to curb this growth and emission of large quantities of HFCs. More recently, the United States Environmental Protection Agency (EPA) announced proposed rules to remove some of the HFCs by application from their approved list of refrigerants. The refrigerant landscape has changed significantly and continues to evolve as these factors come into play. In response to a demand for refrigerants with lower climate impact, natural refrigerants have seen resurgence, made possible in large part due to the advent of electronics and software to make natural refrigerant systems more efficient. New synthetic refrigerants have also been developed, more efficient than existing HFCs and having less impact on the climate. We are looking at a future with more options than we have ever had before – which means that we have to be careful in how we make our choices to minimize or eliminate unintended negative consequences.

How is the regulatory burden impacted by installing low charge ammonia refrigeration systems? With the rapidly growing interest, development and application of limited or low charge ammonia systems, there is an increasing need for market awareness and definition of what the benefits and/or implications are from a regulatory and code perspective for such a system, as compared to larger traditional or existing ammonia systems. For example, codes and standards such as OSHA, IIAR, ASHRAE, IBC, IMC and UMC all have various design references and/or criteria related to the quantity of refrigerant in a system, and specify actions or designs that must be undertaken as a result of their specific refrigerant threshold quantity (TQ). This paper will seek to identify these regulated threshold quantities among the various applicable codes or standards so that designers, contractors and end users can better understand the fact or fiction of the various threshold requirements.
​This is a very large and broad undertaking because there are so many regulations, codes and standards that may or may not apply to all users. Therefore, the paper is also meant to set the stage for continued investigation, collaboration and validation on the subject matter. Many of the regulations and codes have been coordinated over the years and contain some common requirements. However, as shown in this paper, there is a lack of refrigerant threshold quantities related to charge management, as well as a lack of discussion on refrigerant quantity guidelines. Nevertheless, technological advances and industry awareness now provide a real opportunity to incorporate new TQ’s into the regulations and codes. This continued work needs to influence regulatory agencies and code writing bodies to update their documents and to keep pace with the tremendous benefits that low charge technology provides the ammonia refrigeration industry.

Alkylbenzene lubricants have been a good solution in ammonia plants to increase the oil drain interval and reduce the amount of residues in the system when using mineral oil. Nowadays there are more synthetic oils that can be used to do this job. This paper tries to show that these alkylbenzene lubricants are still valid and give a good performance at reasonable prices.

2015 International Technical Program
All International Technical Papers are available in their original presented language and English. 

Un análisis comparativo de varios componentes del ciclo usando amoníaco y R-134a bajo las mismas condiciones de entrada en el evaporador y el condensador mostró que el amoníaco tiene eficiencia de recuperación de calor mejor que R-134a. Además, el ciclo de amoníaco tiene mucho menos caudal másico comparado con R-134a, que resulta en un sistema mucho más pequeño comparado con el de R-134a.

Prospects of Ammonia Based Ocean Thermal Energy Conversion (OTEC) Systems
 Author: Zahid Ayub, Ph. D., P.E. and Samuel Sami, Ph. D.,  P.E.

This paper explores the potential use of ammonia in Ocean Thermal Energy Conversion (OTEC). Different types of advanced heat transfer equipment are discussed for use as vaporizer, condenser and regenerator. Pros and cons of each option are briefly discussed. An overall comparison between ammonia and R-134a based system is presented using a low temperature Rankine cycle.
A comparative analysis of various components of the cycle using ammonia and R-134a under the same input conditions at the evaporator and condenser showed that ammonia has better heat recovery efficiency compared to R-134a. Furthermore, the ammonia cycle has significantly less mass flow rate compared to R-134a, which results in much smaller system compared to that of R-134a.

 室内滑雪场的设计和运行要考虑到很多问题，比如人体舒适性的需求、人工造雪的质量、系统的节能运行等等。众所周知，室内滑雪场的很大一部分能量是其制冷系统所消耗，由于目前很多室内人工滑雪场使用的是氨制冷系统，因此本文将阐述使用氨制冷系统的室内滑雪场的能耗情况，并讨论了相应的节能改进策略。首先给出了四种常用的人工造雪方法以及氨制冷系统的原理，进而给出了不同造雪方法室内雪场的制冷负荷、装机电量的对比以及全年能耗情况；接下来讨论了不同的节能技术如热回收技术、雪场的地下蓄冷技术、雪场道结构优化以及雪水回收技术及其应用等。最后，通过一个正在进行的工程实例展示了这些不同的节能技术在考虑能耗效率、运行安全性和稳定性以及经济性等方面的综合应用。

Energy Efficiency Improvement Strategies of Ammonia-Based Refrigeration Systems used in Indoor Snow Domes  
Author: Dr. Yiqiang Jiang and Ian Zhao

With reference to the design and operation of an indoor snow dome, many factors should be considered including the requirement of human body comfort, the quality of snow, energy saving operation and so on. As we know, the refrigeration system consumes most of the energy in an indoor snow dome and ammonia-based refrigeration systems are widely used in indoor snow domes. Therefore, the objective of this paper is to discuss the energy consumption and energy efficiency improvement strategies for ammonia-based refrigeration systems used in snow domes. First, it introduces four kinds of snowmaking methods and the principles of ammonia-based refrigeration systems used in the indoor snow domes. Second, it provides the refrigeration load and energy consumption of each system in a specified situation, followed by a discussion of different energy efficiency technologies: heat recovery technology and its application and thermal storage in snow base. Finally, a practical engineering example is given to show how to apply these energy efficiency strategies comprehensively to such aspects as energy efficiency, operation possibility, safety and economic viability.

O presente artigo relata uma investigação experimental do processo de drop-in do R22 substituindo-o pelos hidrocarbonetos propano e propileno, bem como pelo HFC438A em um sistema de refrigeração de 15 kW. A bancada experimental foi composta basicamente de um compressor semi-hermético, operado por um inversor de frequência, trocadores de calor de tubos concêntricos e uma válvula de expansão eletrônica. Os testes foram realizados por sucessivas substituições do refrigerante, sem alterar quaisquer componentes, nem mesmo o óleo lubrificante, retratando um típico processo de drop-in. Os principais parâmetros foram variados para verificar-se a faixa de operação e desempenho de cada refrigerante e, em seguida, estes resultados foram comparados à referência, R22. Os resultados experimentais mostraram que os refrigerantes naturais apresentaram os maiores valores de coeficiente de desempenho, COP, e os resultados para HFC438A permaneceram abaixo dos resultados do R22, obtendo-se o pior desempenho. Em relação ao impacto ambiental, utilizando TEWI, o propano e o propileno apresentaram os melhores resultados; entretanto, o HFC438A apresentou o maior impacto ambiental.

Experimental Evaluation of Propane, Propylane and HFC438A as Drop-in Replacements for an R22 System
Author: Enio P. Bandarra Filho

This paper describes an experimental investigation of the application of hydrocarbons propane and propylene as well as HFC438A as drop-in replacements for R22 in a 15 kW refrigeration system. The experimental system was composed basically of a semi hermetic compressor operated by a frequency inverter, tube in tube heat exchangers and an electronic expansion valve. The tests were performed by replacing the refrigerant without changing any components, not even the lubricant oil, as typical in a drop-in process. The main parameters were varied to verify the range and performance of each refrigerant and then compared to the reference, R22. The natural refrigerants presented the best coefficient of performance–COP–while HFC438A yielded the worst performance, below that of R22. Using TEWI as a benchmark for environmental impact, propane and propylene presented the best results while HFC438A had the worst impact.

Los costos de agua y energía eléctrica afectan la operación y el diseño de un sistema de refrigeración con amoníaco. Los condensadores enfriados por aire consumen más energía que los condensadores evaporativos, pero también incrementan el consumo del compresor al tener mayor presión de condensación. Sin embargo, aunque los condensadores evaporativos ahorran energía, también consumen agua. Cuando los costos del agua son altos, la solución de un condensador híbrido, enfriado por agua en horas de altas temperaturas y enfriado por aire en horas de bajas temperaturas, puede ser una solución viable. Este trabajo analiza y compara los consumos de 3 sistemas de refrigeración, uno con cada tipo de condensador, usando Bogotá, Colombia como ejemplo para calcular los consumos eléctricos y de agua en cada hora de un año ejemplo basado en la temperatura ambiente de cada hora. En el caso Bogotá, por sus altos costos de agua, y por sus temperaturas ambiente, la opción del condensador híbrido resulta ser la mejor, aunque el retorno de inversión comparado al evaporativo es de 8-10 años. Este retorno se reduce a la mitad cuando el costo del agua incrementa 10%. En el futuro, el costo del agua seguirá incrementando en muchas ciudades y el análisis de Bogotá se podrá aplicar más y más.

Hybrid Condensers and their Advantages in Ammonia Systems
Author: Raul Perea

Energy and water costs affect the operation and design of an ammonia refrigeration system. Air-cooled condensers consume more energy than evaporative condensers, but also increase the energy consumption of the compressor because of the higher condensation pressure. However, even though evaporative condensers consume less energy, they also consume water. When water costs are high, hybrid condensers, which are cooled by water when temperatures are high and cooled by air when temperatures are low, may be a viable solution. This paper analyzes and compares the energy and water costs of 3 refrigeration systems, each with a different condenser, using Bogota, Colombia as an example, to calculate the hourly consumptions based on the historical ambient temperatures for a sample year. In this case, because of the high water costs in Bogota and the distribution of ambient temperatures, the lowest operating cost option is the hybrid condenser. However, the payback period compared to an evaporative condenser is 8-10 years. This payback period depends on water costs and can be reduced to half if water costs increase by 10%. In the future, water costs will continue to increase in many cities making the analysis made for Bogota more and more relevant.