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Typical Pre-Commissioining and Start-Up Procedures
Published in Maija Virta, HVAC Commissioning Guidebook, 2021
The head can be converted to a pressure using the following formulas (water pump): P (kPa) = 9.81 * head (m)P (bar) = 0.0981 * head (m)P (psi) = 0.43 * head (ft.) Suction cavitation occurs when the pump suction is under a low-pressure/high-vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump, where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure.
Corrosion, Wear, and Degradation of Materials
Published in Mahmoud M. Farag, Materials and Process Selection for Engineering Design, 2020
Cavitation is a related type of wear, which occurs when a liquid containing dissolved gas enters a low-pressure region. Gas bubbles precipitate from the liquid and then subsequently collapse when the pressure increases again. The collapse of the gas bubbles sends high-pressure waves that exert high pressures against the surrounding surface. Cavitation is frequently encountered in hydraulic pumps, propellers, and dams.
Understanding and Recognizing Corrosion
Published in Neville W. Sachs, Practical Plant Failure Analysis, 2019
Cavitation is a form of erosion corrosion where vapor bubbles are formed, and their collapse causes tremendous impact forces. It is usually found in pumps but can occur anywhere that the forces cause vapor bubble development and collapse.
Formation and development of cavitation in a transparent nozzle with double orifices on different planes
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Jinglong Ma, Hua Wen, Shuisheng Jiang, G. Jiang
Cavitation refers to the formation, development and collapse of a vapor or gas bubble in the liquid or 1iquid-solid interface when the local pressure within the liquid decreases to the saturated vapor pressure at the same temperature (Zhang and Xia 1989). When the pressure is higher than its saturated vapor pressure, cavitation zones become unstable and begin to disappear (Min, Zhi, and Hong 2018). From the perspective of reducing energy waste and improving efficiency, there is a trend to use a type of diesel nozzle with a small orifice. In recent years, in order to make air and fuel mix more efficiently, a main objective this research field has been to improve nozzle design (Yan et al. 2017). Based on predicting the spray pattern as well as other subsequent analyzes, an internal flow model inside of the nozzle was established (Rachakonda et al. 2018). Although a large number of scholars have verified the existence of cavitation in the nozzle (He et al. 2015; Sun et al. 2015), it depends on various factors. Furthermore, the detailed mechanism of cavitation in the nozzle has remained uncertain.
Modern techniques for sludge dewaterability improvement
Published in Drying Technology, 2023
Tolga Tunçal, Arun S. Mujumdar
Cavitation is a physical phenomenon in which small vapor bubbles are formed in a liquid due to a local pressure drop. When the formed bubbles collapse, large amounts of energy are released in a small spatial and temporal region, initiating the formation of strong physical forces, i.e., high temperatures, shear forces, microjets, shock waves and oxidative radials, e.g., •OH.[34–36] The extreme conditions created by the collapse of cavitation bubble provide a unique environment to disintegrate the sludge. Hydrodynamic cavitation (HC) method uses orifice plate or venturi channel to control the sludge velocity at a desired level.[34,35] It has been reported that HC is regarded as an effective, easily scalable, and cost-effective process compared to venturi and orifice designs and they have also lower specific energy consumption, at the same cavitation intensity.[35]
Large scale strategy for the extraction of oil from sesame seed: scalable approach
Published in Indian Chemical Engineer, 2023
Jayeshkumar S. Mevada, Yogeshsing N. Rajput, Shaziya Chowdhary, Shirley Kokane, Faith Dias, Ranjeet B. Doke, Ravindra D. Kulkarni, Amit P. Pratap, Aniruddha B. Pandit
In supercritical fluid extraction, it is difficult to maintain the lower temperature and high pressure throughout the process, giving rise to challenges against its scalability and feasibility issues. They have also not reported any significant rise in extraction efficiency compared to conventional methods [20]. In such conditions, ultrasound extraction has shown to be a much more effective extraction technology due to its very low time of operation and higher extraction yield. The cavitation phenomena involve nucleation, bubble growth, and bubble implosion, which results in the massive release of energy in the form of high pressure (100–5,000 bars) and temperature (1,000–10,000 K). Depending on the mode of generation, cavitation is generally classified into four types such as acoustic, hydrodynamic, optic, and particle cavitation. Among these, acoustic cavitation and hydrodynamic cavitation (HC) is widely used for cell disruption and process intensification for physical, chemical and biological processes [21]. The major challenge associated with ultrasound-assisted extraction is the energy consumption; hence it is not scalable. But certain advantages such as preservation of the nutritional quality, reduced processing time, and increased extraction efficiency make the cavitation process promising for large-scale operation [22–25]. The challenges associated with the higher energy requirement required bring prime focus on the scale-up of the process.