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Commercial Operation of Algal Technology: A Case Study and Techno-economic Analysis
Published in Shashi Kant Bhatia, Sanjeet Mehariya, Obulisamy Parthiba Karthikeyan, Algal Biorefineries and the Circular Bioeconomy, 2022
Patrizia Casella, Angela Iovine, Gian Paolo Leone, Sanjeet Mehariya, Tiziana Marino, Antonio Molino
The plant can be loaded with 0.5–1 kg of dry microalgae for a day in a vessel extractor (E-201) with a volumetric capacity equal to 0.5 L. CO2 was pumped in the vessel through the pumping system P-201 after CO2 was cooled by the condenser subcooling device (CO-201). The separator worked for the separation of valuable compounds from CO2. Carbon dioxide was recovered and reused for other extraction processes. Before extraction, carbon dioxide was stored outside in a tank as a liquid state at 50 atm and at room temperature in equilibrium with the gaseous phase located on the top. In the condenser/subcooling system CO-201, carbon dioxide reached a temperature of –5°C by using water and ethylene glycol as cooling fluids. After carbon dioxide was subcooled for the pumping through P-201 pump at a pressure of 30–60 bar. According to the experimental tests, the maximum discharge pressure was recorded around 350 bar. Carbon dioxide passed across the heat exchanger HE-201, that used diathermic oil, as thermal carrier, to reach a temperature of 100–180°C. CO2 temperature remained invariable thanks to the heating circuit positioned between the walls of the chamber and the steel cylinder.
Flow of Fluids
Published in Siddhartha Mukherjee, Process Engineering and Plant Design, 2021
Figure 5.16 illustrates a typical curve for centrifugal compressors. The inlet flowrate is on the X-axis and the discharge pressure is on the Y-axis. With an increasing flowrate, the discharge pressure developed by the compressor decreases. The flowrate versus the discharge pressure curves are shown at different speeds of the compressor. The surge points at different speeds are shown as a surge line. The surge control line is also shown. The antisurge flow is considered at 10% higher than the surge flow. The choking or the stonewall condition occurs when the compressor operates at very high flowrate and flow through the compressor reached close to the sonic velocity and therefore cannot be increased further. The choking or the stonewall line is also shown.
Compressor Types
Published in Tony Giampaolo, Compressor Handbook, 2020
As the screws rotate the process gas is drawn into the inlet or suction port. Gas is compressed by rotary motion of the two intermeshing screws. The gas travels around the outside of the screws starting at the top and traveling to the bottom while it is being moved axially from the suction port to the discharge port. The location of the discharge port determines when compression is complete. A slide valve over the discharge ports is used to control or vary the discharge pressure.
The optimum discharge pressure of CO2-based refrigeration cycles operating under subcritical and transcritical conditions
Published in International Journal of Ambient Energy, 2023
Devendra Kumar Sharma, Mihir Mouchum Hazarika, Maddali Ramgopal
In the present study the quantitative impact of compressor performance, evaporator temperature and degree of superheat on optimum discharge pressure of CO2-based refrigeration cycles is presented. Using simple thermodynamic equations, efforts are made to identify those parameters which influence the optimum heat rejection pressure across the critical point. Based on the study, a single optimum discharge or heat rejection pressure equation is developed, which is suitable for subcritical and transcritical cycles. The developed equation can be of importance where CO2-based systems are subjected to varied operating conditions. Such systems tend to operate near critical points in subcritical and transcritical zones. To maximise the performance of the CO2-based systems for such operations, discharge/heat rejection pressure can be controlled in accordance with the developed optimum discharge pressure equation.
Thermodynamic Analysis of Air Conditioning System for a Passenger Vehicle with Suction Line Heat Exchanger Using HFO-1234yf
Published in Heat Transfer Engineering, 2023
Rajendran Prabakaran, Dhasan Mohan Lal, Sung Chul Kim
The effects of the EIAT on the variations in the discharge pressure/temperature and pressure ratio of the compressor are shown in Figure 5 for the three compressor speeds. Figure 5a and b displays that the compressor discharge pressure and its associated temperature increased as the compressor speed and EIAT increased. The increase in EIAT enlarged the difference in temperature between the coil and cabin, resulting in a larger load on the cooling coil. Therefore, both the evaporation pressure and temperature increased, which resulted in high discharge pressure and temperature. For the considered compressor speeds, the rise in discharge pressure and temperature with increase in EIAT was found to be 2.2 bar and 4.5 °C for HFC-134a and 2.1 bar and 5.2 °C for HFO-1234yf. The variations in the discharge pressure between the considered refrigerants increased as the compressor speed and EIAT increased. However, the difference in discharge temperature decreased. Overall, the discharge pressure and associated temperature of the VAC unit for HFO-1234yf were seen as 0.1–0.9 bar and 1.1–2.6 °C, respectively, lower than those of HFC-134a.
Numerical and thermo-energy analysis of cycling in automotive air-conditioning operating with hybrid nanolubricants and R1234yf
Published in Numerical Heat Transfer, Part A: Applications, 2023
M. Z. Sharif, W. H. Azmi, M. F. Ghazali, N. N. M. Zawawi, H. M. Ali
The comparison between experimental data and the AAC simulation model is undertaken to validate the model’s accuracy. The accuracy of the data from the AAC simulation model is tested under similar settings to the steady-state experimental conditions. The experimental conditions include the refrigerant mass flow rate, the suction and discharge pressure of the compressor, and compressor speed. The data from simulation models were collected for two crucial thermodynamic parameters. The two thermodynamic parameters, temperature, and pressure were evaluated at the critical point of the AAC system. Figure 13 compares 15 test data points, which is useful for AAC performance analysis. The comparison was made between simulation predictions and experimental data for refrigerant state enthalpy at points h1, h2, and h5, estimated using pressure and temperature at the locations indicated in Figures 1 and 3. As demonstrated in Figure 13, almost 80% of the enthalpy data points were accurately predicted by the simulation model within 5% of the experimental data. In addition, 20% of the enthalpy data points were predicted with an accuracy of 15% relative to the experimental data. It may be inferred that the little difference between experimental and simulation-predicted data verified the present AAC dynamic model’s capability to access the AAC system’s performance. However, the AAC dynamic model slightly overpredicted the enthalpy data point h5, especially at the high compressor speed.