Method of Measuring the Vapor Pressure and Concentration of Fluids using VLE and Vibrating Tube Densitometer Apparatuses

This work presents the vapor pressure and concentration measurement of newly discovered environmentally friendly refrigerants 1, 1-difluoroethane (R152a) and 1,1,1,3,3-Pentafluorbutane (R365mfc), besides their mixture. The experimental procedure used in this work was a VLE recirculation type apparatus in which the liquid phase is circulating around the equilibrium cell. Special attention was given to enable a highly accurate vapor pressure measurement up to maximum pressure of 25 bar. The liquid sampling method was perfected through the use of quick plug valves at the circulation loop of the VLE apparatus. This approach has a great effect in solving the problems of changing the volume of the fluids inside the equilibrium cell, since the sampling unit needs a minimum amount of fluid to be sampled. Moreover a new method for measuring the concentration of this mixture through using a vibrating tube densitometer apparatus (DMA-HPM) has been realized. This apparatus was able to supply data in the temperature range of -10 to 200 °C and pressure of 0 to 1400 bar, with an uncertainty of 0.1%. The experimental data was validated using the Volume Translated Peng Robinson Equation of State and high precision fundamental equations of state by McLinden from National Institute of Standard and Technology (NIST). Other models such as Modified Huron Vidal, Wong Sandler, Lee Kesler and Hoffman Florin have been verified. Amongst all the models, McLinden et.al model achieved vapor pressure deviations of less than 0.073% for R365mfc.The concentration deviations reached -3.1%,-9.8% for a composition of 33.6% R152a and 44.1% R365mfc respectively. The deviations of VTPR and VTPR-MHV2 have led to similar results data in the pure fluids and the mixture respectively.

Density of the Refrigerant Fluids of R365mfc and R152a: Measurement and Prediction

This work presents the density of new environmentally friendly refrigerants 1,1-difluoroethane (R152a) and 1,1,1,3,3-Pentafluorbutane (R365mfc) in their pure fluid and mixture. The density is covered in the temperature range of -10-450C and the pressure range of p=0.65-10.47 bar. The density is measured by a vibrating-tube densitometer (DMA-HPM) manufactured by Anton Paar. The apparatus supplies data in the temperature range of -10°C to 200 °C and a pressure range of 0 to 1400 bar, with an uncertainty of 0.1%. The experimental data is validated using the ‘Volume Translated Peng Robinson Equation of State’ and high precision fundamental equations of state by Outcalt and McLinden from the National Institute of Standard and Technology (NIST). Outcalt and McLinden model achieve deviations less than 0.56% for R365mfc and 0.51% for R152a. The deviations of VTPR are within 2.5% and 15% in the pure fluid and mixture respectively.

Temperature Measurement And Calibration Setup (TH1)

The work investigated the responses of measuring and calibrating the temperature in the range of 30 to 60°C using a setup of TH1. The setup was configured with an ice flask, sensor installing unit, an electrical console, and a regulating bath which can withstand temperatures in the range of 0°C to 100°C. Various sensors such as industrial platinum resistance thermometer PT100IND, type K thermocouple, and a thermistor were installed. The setup was configured with highly accurate reference sensors of platinum resistance device PT100, with NAMAS calibration certificate, and temperature with linearized output. Extra reference sensors were installed such as bi-metallic and liquid-in-glass thermometers to ensure high accuracy in measuring and calibrating data. The experimental data revealed that the PT100IND resistance changed linearly with temperature. The calibration error of PT100IND, according to the temperature data, reached a maximum value of less than 1.60%. According to the temperature scale of ITS-90, the standard parameters of calibration equation of Callendar-van Dusen for PT100IND provided errors of less than 5.5% and 3.2% respectively. The type K thermocouple delivered a linear change in output with highly stable temperature response. According to NIST data, the calibration error for the thermocouple reached a maximum value of less than 0.98%. The thermistor resistance revealed weak and late response at low temperature, but its sensitivity improved with increasing temperature. The calibration error according to experimental data and the Steinhart-Hart equation for the thermistor sensor was less than 0.30%

Regenerative Gas Turbine Power Plant: Performance & Evaluation

In this work, comprehensive operational and conceptual design basics of the Regenerative Gas Turbine were studied and applied to the Khartoum North Thermal Power Station, Sudan, which has a total power of 187MW. The analysis and results of this work were executed using the Engineering Equation Solver.The results show that, the increasing the effectiveness of the regenerative cycle increased the thermal efficiency. However, there is a turning point of compressor inlet temperature, after which the further increase of temperature and regenerator effectiveness will lead to decline in the thermal efficiency of the cycle. At lower regeneration and moderate regenerator effectiveness, the increase in compression ratio leads to an increase in thermal efficiency of the cycle. At the highest values of regeneration effectiveness, the increase in compression ratios reduced the thermal efficiency of the cycle. The results revealed that regeneration is more effective at lower pressure ratios, ambient temperatures, and low minimum (compressor) to maximum (combustor) temperature ratios. An increase in regeneration effectiveness decreases the specific fuel consumption for lower and moderate compression ratios. At higher compression ratios, increasing regenerator effectiveness leads to an increase in the specific fuel consumption (SFC) of the cycle. At low and moderate compressor inlet temperature, increasing the regenerator effectiveness decreases fuel demand in the combustor, which reflects in decreasing the heat rate to the combustor especially at higher regenerative effectiveness (e=95%). As the effectiveness varies between 10-75%, the compressor inlet temperature varies from 200K to 350K and the regenerator exhaust temperature exhibited different profiles according to the conditions of inlet temperature. It was found that power curve declines smoothly due to the increase in irreversibility of regeneration cycle and remains high at higher turbine inlet temperatures. Compressor inlet temperatures between 100-330K increase the regeneration effectiveness varying between 10-95%, resulting a in different profile of the combustor inlet temperature. The mass flow rate of the fuel in the combustor decreases with increasing regeneration effectiveness at lower compressor inlet temperatures. At higher inlet temperatures, the fuel flow rate will gradually increase with the regeneration effectiveness due increasing irreversibilities of the regenerator. For a compression ratio of 15, the fuel mass flow rate reaches the lowest value of (6.30 kg/sec) at the lowest ambient temperature of 200 K and a regenerative effectiveness of 95%. The increase of the lower heating value (LHV) leads to a gradual increase in the thermal efficiency of the regenerative gas turbine (RGT), due to increasing cycle power and combustor capacity. The results concluded that the regeneration effectiveness is higher at low and moderate compressor inlet temperatures and compression ratios, through which, avoiding the regenerator’s irreversibility is possible