No abstract

Recently, new environment-friendly energy conversion technologies are required for using energy resources valid to power generation. Accordingly, low-grade heat sources as solar heat, geothermal energy, and waste heat, which have available temperatures ranging between 60 and 200 °C, are supposed as applicants for recent new generation energy resources. As an alternative energy source, such low-grade heat sources usage generating electricity with the help of power turbine cycles was examined through this study. Such systems have existing technologies applicable at low temperatures and a compact structure at low cost, however, these systems have a low thermal efficiency of the Rankine cycles operated at low temperatures. An organic Rankine cycle is alike to a conventional steam power plant, except the working fluid, which is an organic, high molecular mass fluid with a liquid-vapor phase change, or boiling point, at a lower temperature than the water-steam phase change. The efficiency of an organic Rankine cycle is about between 10% and 20%, depending on temperature levels and availability of a valid fluid.

This work is an energy study of an organic Rankine cycle (ORC) for the recovery of thermal energy by comparing three organic fluids. This cycle is considered to be a promising cycle for the conversion of heat into mechanical energy suitable for low temperature heat sources; it uses more volatile organic fluids than water, which generally has high molecular weights, thus allowing operating pressures at temperatures lower than those of the traditional Rankine cycle. A thermodynamic model was developed using the Engineering Equation Solver (EES) software to determine its performance using different working fluids (toluene, R245fa and R123) under the same operating conditions, taking into account the effect of certain operating parameters and the selection of organic fluids on cycle performance. The results obtained show that the toluene organic fluid has the best thermal efficiency of the cycle compared to the other fluids; 14.38% for toluene, 13.68% for R123 and 13.19 for R245fa.

Abstract-This paper is about commercial buildings energy consumption survey (CBECS) benchmarking database consept, its applications and related applications in Turkey. CBECS is useful for energy efficiency in new commercial building constructions, which is a key target to control and lower U.S. nation-wide energy use.Determining energy consumption of buildings is a key target for energy efficiency. Building energy efficiency is crucial especially for economical and climate change concerns. Improving energy efficiency in commercial buildings is useful in order to decrease energy use, owner operating costs, and carbon footprint of the buildings.The aims are to estimate life-cycle energy savings, cost performance of energy efficiency and carbon emission reduction in new commercial buildings utilizing an integrated design, and estimate results. Obtaining energy consumption of buildings can be utilized to decrease energy usage in new commercial buildings by 20-30% on average and up to over 40%. Thus, improved efficiencies permit smaller, cheaper HVAC equipment usage.

C urrently, a continuous increase in energy consumption is noted which has led to environmental problems such as global warming and the depletion of fossil fuels. Total global energy consumption increased from 575 quadrillion British thermal units (BTUs) in 2015 to 736 quadruplets in 2040, with an increase of 28% [1]. Organic Rankine Cycle is one of the most commonly utilized technologies for producing electricity from low-grade heat [2], which can be derived from Geothermal [3,5], Biomass [6,7], Industrial waste [8] and solar energy [9,10]. The organic fluids used by organic Rankine rings are usually: hydrofluorocarbon refrigerants, ammonia, butane, isopentane, toluene depending on the nature of the fluid, isentropic expansion from the dew curve may conserve, decrease, or increase the vapor titer. It is, in fact, the slope of the dew curve in the Mollier diagram that explains this phenomenon specific to the nature of the fluid. The aim of this study is to estimate the mechanical power that can be provided by an organic rankine cycle by studying the effect of the evaporation temperature and the choice of the organic fluid adapted to this type of energy conversion system and to find the organic rankine cycle performance by comparing three different organic fluids; Toluene, R245fa and R123.