{"id":1662,"date":"2021-07-19T14:23:08","date_gmt":"2021-07-19T18:23:08","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/thermo1\/chapter\/5-5-application-of-the-mass-and-energy-conservation-equations-in-steady-flow-devices\/"},"modified":"2022-09-12T17:53:39","modified_gmt":"2022-09-12T21:53:39","slug":"5-5-application-of-the-mass-and-energy-conservation-equations-in-steady-flow-devices","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/thermo1\/chapter\/5-5-application-of-the-mass-and-energy-conservation-equations-in-steady-flow-devices\/","title":{"raw":"5.3 Applications of the mass and energy conservation equations in steady flow devices","rendered":"5.3 Applications of the mass and energy conservation equations in steady flow devices"},"content":{"raw":"
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5.3.1 Turbines and compressors<\/h2>\r\n

Turbines and compressors are common energy conversion devices, in which the energy of a working fluid is converted to mechanical energy or vice versa. A typical turbine consists of rotor blades attached to a shaft, which is free to rotate. Figure 5.3.1<\/a> shows the main components of a hydraulic turbine. During the operation of a turbine, a working fluid (e.g., steam, gas, wind or water) flows continuously over a row of highly curved blades, creating a torque on the blades. In this process, the energy of the working fluid is converted to the mechanical energy of the rotating shaft. Consequently, the pressure and temperature of the fluid gradually decrease in the turbine. Figure 5.3.2<\/a> illustrates the energy conversion in a wind turbine. The wind energy is first converted to the mechanical energy of the shaft and gearbox, then converted to the electrical energy through the generator.<\/p>\r\n \r\n

Compressors work in the opposite way to turbines. Compressors consume shaft power in order to increase the pressure of a working fluid, typically a gas. In a dynamic compressor, such as a centrifugal compressor, the increase of the gas pressure is achieved by forcing the gas into narrow passages formed by adjacent blades, which rotate around a shaft. Figure 5.3.3<\/a> shows a centrifugal compressor driven by an electric motor. In a reciprocating compressor, the increase of the gas pressure is achieved by the decrease of the gas volume as the piston, driven by a crank-shaft, compresses the gas. Figure 5.3.4<\/a> animates the expansion and compression processes in a reciprocating compressor. In both dynamic and reciprocating compressors, the mechanical energy of the rotating shaft or crank-shaft is converted to the energy stored in the fluid. <\/a> As a result, the pressure of the fluid increases in the compressor.<\/p>\r\n\r\n<\/div>\r\n

\u00a0<\/em><\/div>\r\n
<\/div>\r\n
\r\n\r\n[caption id=\"attachment_1186\" align=\"aligncenter\" width=\"269\"]\"Hydraulic<\/a> <\/a>Figure 5.3.1<\/strong>\u00a0Hydraulic turbine<\/em>[\/caption]\r\n\r\n<\/div>\r\n
\r\n\r\n[caption id=\"attachment_2350\" align=\"aligncenter\" width=\"500\"]\"Wind<\/a> <\/a>Figure 5.3.2<\/strong> Wind turbine schematic showing the energy conversion<\/em>[\/caption]\r\n\r\n<\/div>\r\n
\r\n\r\n[caption id=\"attachment_1188\" align=\"aligncenter\" width=\"276\"]\"Centrifugal<\/a> <\/a>Figure 5.3.3<\/strong> Centrifugal compressor<\/em>[\/caption]\r\n\r\n[caption id=\"attachment_2354\" align=\"aligncenter\" width=\"440\"]\"Reciprocating<\/a> Figure 5.3.4<\/strong> Reciprocating compressor: animation of the compression and expansion processes<\/em>[\/caption]\r\n

Figure 5.3.5<\/a> illustrates the flow of energy through a turbine and a compressor. A typical turbine or compressor has one inlet and one outlet. We may apply the following assumptions to typical turbines and compressors:<\/p>\r\n\r\n