2001 TSE: NSF/EPA Partnership for Environmental Research: A Theoretical and Experimental Approach to Rapid Screening and Design of Secondary Refrigerants (TSE01-C)

美国制冷和空调行业的氢氟碳化物(HFC)排放量目前约为1300万公吨碳当量(MMTCE)。这一数字预计将在2005年和2010年分别增长到27和38 MMTCE。仅次于汽车冷藏系统的零售食品冷藏占这些排放的25%：一个典型的超市每年泄漏约1吨制冷剂。二次制冷回路有可能将一次制冷剂用量减少到传统制冷系统所需用量的10%。尽管如此，在美国30,000多家超市和300,000家便利店中，只有200家接受了二次制冷。由于利润率与他们的电费相当，零售食品企业担心二次制冷剂可能没有目前直接制冷中使用的氢氟碳化物那么节能。提高这一领域的能效也是政府关注的问题，因为零售食品业目前约占全国用电量的4%。该项目的主要目标是致力于解决以下问题：(A)哪些化合物可以用作二次制冷剂？(B)这些化合物的能效是什么？它与目前用于直接制冷的氢氟碳化物相比如何？(C)这些化合物安全且对环境无害吗？为了回答这些问题，该项目将理论和实验研究相结合，将：(1)开发一个数学模型，该模型选择制冷剂的原子组成，使其在满足环境和化学约束的同时，优化能源效率、制冷剂生命周期的总升温影响以及其他经济和环境目标；(2)设计了求解上述模型的算法程序，克服了问题的组合困难以及性能预测估计技术中与非线性相关的困难；(3)建立了通过测量潜在制冷剂的物理性质来校准数学模型的实验程序；(4)通过实验室合成模型所识别的化合物并在实际制冷设备中测量其热传递性质，对理论结果进行了实验验证。

Hydrofluorocarbon (HFC) emissions from the refrigeration and air conditioning sector in the U.S. currently amount to approximately 13 million metric tons of carbon equivalent (MMTCE). This number is expected to grow to 27 and 38 MMTCE in 2005 and 2010, respectively. Second only to automotive refrigeration systems, retail food refrigeration accounts for 25% of these emissions: a typical supermarket leaks about 1 ton of refrigerants every year. Secondary refrigeration loops have the potential to reduce primary refrigerant charges to as little as 10% of that required in a traditional refrigeration system. Nonetheless, secondary refrigeration has found acceptance in only about 200 out of over 30,000 supermarkets and 300,000 convenience stores in the U.S. With profit margins comparable to their electric bills, retail food enterprises are concerned that secondary refrigerants may not be as energy-efficient as the HFCs that are currently used in direct refrigeration. Improving the energy efficiency in this sector is of government concern as well since the retail food industry currently accounts for approximately 4% of electricity consumption in the nation.The primary goal of this project is to work towards addressing the following questions:(a) What are the families of compounds that can act as secondary refrigeration fluids?(b) What is the energy efficiency of these compounds and how does it compare to that of the HFCs that are currently used in direct refrigeration?(c) Are these compounds safe and environmentally benign?Towards answering these questions, this project integrates theoretical and experimental research that will:(1) develop a mathematical model which selects the atomic composition of a refrigerant in such a way that environmental and chemical constraints are satisfied while the energy efficiency, total warming impact of the refrigerant life-cycle, and other economic and environmental objectives are optimized;(2) devise an algorithmic procedure to solve the above model in a way that overcomes the combinatorial difficulty of the problem as well as difficulties associated with nonlinearities in property prediction estimation techniques;(3) establish an experimental procedure for calibrating the mathematical model through measurement of physical properties of potential refrigerants;(4) verify experimentally the theoretical findings through laboratory synthesis of compounds identified by the model and measurement of their thermal transfer properties in actual refrigeration equipment.