Thermodynamic analysis of a vapor compression refrigeration system

• Grant number: 07/07393-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): April 01, 2008
• Effective date (End): March 31, 2009
• Field of knowledge: Engineering - Chemical Engineering - Chemical Process Industries
• Principal Investigator: José Vicente Hallak d´Angelo
• Grantee: Natalia Bonifacio Marteleto
• Host Institution: Faculdade de Engenharia Química (FEQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

In many chemical industries, refrigeration is a unit operation of great importance, in which chemical engineers play an essential role in many stages like: equipment sizing, refrigerant choice and performance evaluation of refrigeration systems. Traditional techniques used to evaluate these systems use energy balances to estimate losses of energy by heat and work transfer to surroundings. In these cases the efficiency of the refrigeration cycle is expressed by its COP - coefficient of performance. Energy balances are based on the First Law of Thermodynamics but the efficiency of refrigeration cycles must also be evaluate from the point of view of the Second Law of Thermodynamics, which considers the variations that occur in the quality of the energy available. This method of analysis is called "Exergetic Analysis" and it allows to determine not only the magnitude but also the localization of major losses in energy quality in the process, making possible to propose different operational and design conditions seeking for an energy economy in the process. This research project intends to perform a thermodynamic analysis of a experimental vapor compression refrigeration system and also to simulate it in order to study the influence of process variables over exergy losses, evaluating the influence of pressure and temperature in each cycle stream and also the refrigerant mass flow and compressor power. A commercial process simulator (Hysys version 2.2) will be used to simulate the experimental system, generating all thermodynamic data necessary to calculate exergy losses in the cycle. (AU)