A two phase flow nonlinear parameter estimation for capillary tube-suction line heat exchanger

Here we present two-phase flow nonlinear parameter estimation for HFC's flow through capillary tube-suction line heat exchangers, commonly used as expansion devices in small refrigeration systems. The simplifying assumptions adopted are: steady state, pure refrigerant, one-dimensional flow, negligible axial heat conduction in the fluid, capillary tube and suction line walls. Additionally, it is considered that the refrigerant is free from oil and both phases are assumed to be at the same pressure, that is, surface tension effects are neglected. Metastable flow effects are also disregarded, and the vapor is assumed to be saturated at the local pressure. The so-called homogeneous model, involving three, first order, ordinary differential equations is applied to analyze the two-phase flow region. Comparison is done with experimental measurements of the mass flow rate and temperature distribution along capillary tubes working with refrigerant HFC-134a in different operating conditions.

Experimental research on the influence of the air humidity conditions in an air conditioning system

The factors that have influence on the energy consumption of a small air conditioning system that are worth mentioning are the efficiencies of the compressor, evaporator and condenser, the form that the refrigerant flow is controlled, the fan model used, and climatic conditions. Within the climate issue, an interesting factor is that the relative humidity when it comes to the effect that it causes, especially in the performance of the air condenser, which generally is not considered in the projects. This study aims to evaluate the influence of humidity on the coefficient of system performance (COP), seeking to quantify their influence when it happens. The tests were performed on a testing bench, mounted at the Laboratory for Energy Efficiency (LAMOTRIZ) UNESP-Campus Guaratinguetá. In the study, the wet bulb temperature was ranged, keeping the rotation of the scroll compressor with application of a frequency inverter in its best performance. The test bench is provided with a supervisory system of data collection that is also able to control all functions of the bench. In the results, there was a significant influence, particularly when comparing high humidity conditions with low humidity, noting that only over 65% relative humidity is that significant changes are observed in the COP of the system. © 2013 Elsevier Inc.

Simulação do escoamento bifásico da mistura óleo-refrigerante através da folga radial de compressores rotativos de pistão rolante

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Simulação computacional do escoamento bifásico com formação de espuma da mistura óleo-refrigerante R134a ao longo de um tubo reto de seção circular constante

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise numérica de condensadores do tipo arame-sobre-tubo usados em refrigeradores domésticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelagem do escoamento ao longo de evaporadores de serpentina com tubos aletados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise numérica de evaporadores do tipo Roll-Bond usados em refrigeradores domésticos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelagem do escoamento transiente ao longo de trocadores de calor tubo capilar-linha de sucção

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Levantamento de coeficientes de desempenho de armazenador térmico associado a refrigerador doméstico modificado

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A influência da aplicação de fluído de corte no torneamento da liga de aluminio AA 7075

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

An assessment of the economic impact of climate change on the Agriculture, Energy and Health sectors in Trinidad and Tobago

This report analyses the agriculture, energy, and health sectors in Trinidad and Tobago to assess the potential economic impacts of climate change on the sectors. The fundamental aim of this report is to assist with the development of strategies to deal with the potential impact of climate change on Trinidad and Tobago. It also has the potential to provide essential input for identifying and preparing policies and strategies to help advance the Caribbean subregion closer to solving problems associated with climate change and attaining individual and regional sustainable development goals. Some of the key anticipated impacts of climate change for the Caribbean include elevated air and sea-surface temperatures, sea-level rise, possible changes in extreme events and a reduction in freshwater resources. The economic impact of climate change on the three sectors was estimated for the A2 and B2 IPCC scenarios until 2050. An exploration of various adaptation strategies was also undertaken for each sector using standard evaluation techniques. The study of the impact of climate change on the agriculture sector focused on root crops, green vegetables and fisheries. For these sectors combined, the cumulative loss under the A2 scenario is calculated as approximately B$2.24 and approximately B$1.72 under the B2 scenario by 2050. This is equivalent to 1.37% and 1.05% of the 2008 GDP under the A2 and B2 scenarios, respectively. Given the potential for significant damage to the agriculture sector a large number of potential adaptation measures were considered. Out of these a short-list of 10 potential options were selected by applying 10 evaluation criteria. All of the adaptation strategies showed positive benefits. The analysis indicate that the options with the highest net benefits are: (1) Building on-farm water storage, (2) Mainstreaming climate change issues into agricultural management and (3) Using drip irrigation. Other attractive options include water harvesting. The policy decisions by governments should include these assessments, the omitted intangible benefits, as well as the provision of other social goals such as employment. The analysis of the energy sector has shown that the economic impact of climate change during 2011-2050 is similar under the A2 (US$142.88 million) and B2 (US$134.83 million) scenarios with A2 scenario having a slightly higher cost (0.737% of 2009 GDP) than the B2 scenario (0.695% of 2009 GDP) for the period. On the supply side, analyses indicate that Trinidad and Tobago’s energy sector will be susceptible to the climate change policies of major energy-importing countries (the United States of America and China), and especially to their renewable energy strategies. Implementation of foreign oil substitution policy by the United States of America will result in a decline in Trinidad and Tobago’s Liquefied Natural Gas (LNG) export (equivalent to 2.2% reduction in 2009 GDP) unless an alternative market is secured for the lost United States of America market. China, with its rapid economic growth and the highest population in the world, offers a potential replacement market for Trinidad and Tobago’s LNG export. In this context the A2 scenario will offer the best option for Trinidad and Tobago’s energy sector. The cost-benefit analysis undertaken on selected adaptation strategies reveal that the benefit-cost ratio of replacing electric water heaters with solar water heaters is the most cost-effective. It was also found that the introduction of Compact Fluorescent Light (CFL) and Variable Refrigerant Volume (VRV) air conditioners surpasses the projected cost of increased electricity consumption due to climate change, and provides an economic rationale for the adoption of these adaptation options even in a situation of increased electricity consumption occasioned by climate change. Finally, the conversion of motor fleets to Compressed Natural Gas (CNG) is a cost-effective adaptation option for the transport sector, although it has a high initial cost of implementation and the highest per capita among the four adaptation options evaluated. To investigate the effect of climate change on the health sector dengue fever, leptospirosis, food borne illnesses, and gastroenteritis were examined. The total number of new dengue cases for the period 2008 to 2050 was 204,786 for BAU, 153,725 for A2 and 131,890 for the B2 scenario. With regard to the results for leptospirosis, A2 and B2 seem to be following a similar path with total number of new cases in the A2 scenario being 9,727 and 9,218 cases under the B2 scenario. Although incidence levels in the BAU scenario coincided with those of A2 and B2 prior to 2020, they are somewhat lower post 2020. A similar picture emerges for the scenarios as they relate to food-borne illnesses and to gastroenteritis. Specifically for food-borne illnesses, the BAU scenario recorded 27,537 cases, the A2 recorded 28,568 cases and the B2 recorded 28,679 cases. The focus on the selected sources of morbidity in the health sector has highlighted the fact that the vulnerability of the country’s health sector to climate change does not depend solely on exogenously derived impacts, but also on the behaviour and practices among the population. It is clear that the vulnerability which became evident in the analysis of the impacts on dengue fever, leptospirosis and food-borne illnesses is not restricted solely to climate or other external factors. The most important adaptation strategy being recommended targets lifestyle, behaviour and attitude changes. The population needs to be encouraged to alter their behaviours and practices so as to minimise their exposure to harmful outcomes as it relates to the incidence of these diseases.

Eficiência energética em sistemas de refrigeração industrial: estudo de caso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comparação da viabilidade técnica-econômica em condicionamento de ar: compressor a pistão versus compressor rotativo de velocidade variável

Pós-graduação em Engenharia Mecânica - FEG

Redução de consumo de energia eletrica a partir de reaproveitamento de energia termica com uso de ciclo rankine orgânico

This paper is proposed the usage of an Organic Rankine Cycle (ORC) along with waste heat recovery from an inconstant heat source. This method of waste heat recovery with intermittent heat source is part of a technical viability study. This paper also brings up the usage of thermal energy storage as heat source for the ORC. This paper is based on a heat treatment company study in which a natural gas furnace is explored. Data such as mass flow, temperature and specific waste gas heat from this furnace are used through calculations. Calculations are made also based on furnace cycles. This viability study considers a series of working fluids such as ammonia, benzene, R113 and R134a. Results point out that ORC with out thermal storage and using refrigerant fluid ammonia is the best alternative

Modelo distribuído aplicado à análise de evaporadores do tipo tubo aletado

Pós-graduação em Engenharia Mecânica - FEIS