Types Of Organic Fluids Research Articles

Simultaneous molecular and process design for waste heat recovery

Processing streams featuring low temperatures are common in industrial systems. Because of low temperatures it turns out to be a challenge to use these type of streams for energy recovery. This is especially true if water is used as the main fluid for energy recovery since large amounts of energy are required for water vaporization. To cope with this energy problem different types of organic fluids used in Rankine-like thermodynamic cycles have been proposed. However, high cost and sustainability issues (i.e. large toxicity) related to organic fluids call for the design of a new type of working fluids suitable for low-temperature energy recovery. This generation of new working fluids should feature target properties such as high vapor pressure and low flammability and toxicity values. Moreover, the performance of these new working fluids also depends on the operating conditions of the thermodynamic cycle where such working fluids will be used. In this work we address the simultaneous product and process design problem of working fluids for energy recovery from low-temperature energy sources in Rankine-like cycles to obtain improved optimal solutions. We compare the energy recovery performance of both the new family of working fluids and processing conditions against similar energy performance obtained using organic fluids previously used for the same aim. By using a system of coupled cycles, work production was increased. Moreover, the new working fluids feature improved safety margins. The results indicate the benefits of the simultaneous product and process design approach and permit us to identify a family of working fluids with better sustainability characteristics.

Performance analysis of organic Rankine cycles using different working fluids

Low-grade heat from renewable or waste energy sources can be effectively recovered to generate power by an organic Rankine cycle (ORC) in which the working fluid has an important impact on its performance. The thermodynamic processes of ORCs using different types of organic fluids were analyzed in this paper. The relationships between the ORC?s performance parameters (including evaporation pressure, condensing pressure, outlet temperature of hot fluid, net power, thermal efficiency, exergy efficiency, total cycle irreversible loss, and total heat-recovery efficiency) and the critical temperatures of organic fluids were established based on the property of the hot fluid through the evaporator in a specific working condition, and then were verified at varied evaporation temperatures and inlet temperatures of the hot fluid. Here we find that the performance parameters vary monotonically with the critical temperatures of organic fluids. The values of the performance parameters of the ORC using wet fluids are distributed more dispersedly with the critical temperatures, compared with those of using dry/isentropic fluids. The inlet temperature of the hot fluid affects the relative distribution of the exergy efficiency, whereas the evaporation temperature only has an impact on the performance parameters using wet fluid.

Working Fluid Selection for Organic Rankine Cycles from a Molecular Structural Point of View

The optimum working conditions of 11 working fluids under different heat source temperatures for an organic Rankine cycle (ORC) were located in our previous work. In the current work, the system irreversibility of each candidate were calculated and compared at their optimal operating conditions. Obvious variation trends of both the cycle efficiency and irreversibility were found for different types of organic fluids. It is suggested, when selecting working fluid for our ORC system, the critical temperature should be as close as possible to the heat source temperature to achieve high cycle efficiency but avoid large irreversibility. The relationships between the structure of the molecules and the critical temperature of the working fluids are investigated qualitatively and potentially meaningful for the rational selection of proper organic fluids for certain ORCs.

Maximising the working fluid flow as a way of increasing power output of geothermal power plant

This paper presents a method of increasing the power output of a geothermal power plant based on organic working fluid. The power is raised by increasing the flow of geothermal water supplied to the evaporator by means of returning the stream of geothermal water from downstream of the evaporator for a repeated passage through that heat exchanger. Such arrangement increases the flow of the working fluid in the circuit. Analyses have been conducted for a power plant using several types of organic fluids. The results obtained show that there is one optimum evaporation temperature of the working fluid, which depends on the quantity of the recycled geothermal water, at which the capacity of the Clausius–Rankine is the highest.

Detection of organic pollutants in sandy soils via TDR and eigendecomposition

In this study, organic pollutants in sandy soils are detected using a time domain relectrometry (TDR) probe system and eigendecomposition technique. As a demonstration, four types of organic fluids (motor oil, diesel oil, methanol and ethanol) were examined. Samples were prepared with different combinations of deionized water and organic fluid contents. For each experiment, reflected signals were captured by an oscilloscope, and their characteristics were identified using eigendecomposition technique. Autoregressive modeling and singular value decomposition methods were utilized for calculating the eigenvalues. The most significant eigenvalues were then identified based on their relative magnitude. Experimental results indicated that the presented system is sensitive to both water and pore fluid organic contents. For saturated conditions, signature curves were determined for identification of organic and/or water contents in soil pore fluids.

Types and Usages of Drilling Fluids Utilized to Install Monitoring Wells Associated with Metals and Radionuclide Ground Water Studies

AbstractEvaluation for metal and radionuclide contamination associated with selected inactive uranium mill tailings repositories required the installation of monitoring wells in both shallow unconfined and deep artesian aquifer systems. To prevent ionic exchange between the dissolved cationic metals and the cations in bentonitic drilling fluids, organic‐based fluids were used during the drilling and installation of monitoring wells. Experience gained at three western U.S. sites involving inactive uranium mill tailings indicates organic drilling fluids can be used to advance drill holes in soil materials ranging from saturated silts and fine sands to unsaturated gravels. However, it has been determined that certain types of these organic fluids can clog very narrow screen slots and remain present in well discharge, even after several hours of well cleaning. Certain types of organic drilling fluids appear to be preferable for these types of water chemistry studies.