Rankine temperature

The working fluids, such as ammonia and freons, used in refrigerators and heat pumps are more desirable than steam for the very low-temperature Rankine cycles. The reason is that the specific volume of such working fluids at low temperature is much less than that of steam, so the resulting turbine sizes can be much smaller and less expensive. 

Why are working fluids such as ammonia and freons, used in refrigerators and heat pumps, more desirable than steam for the low-temperature Rankine cycles ... 

V = volume, in. m = mole weight of contents R = gas constant T = temperature, Rankine P = pressure, psi... 

A column of hot air (flg. 7.1) weighs less than an equally tall column of cold air, which is shown dotted to form a U-tube manometer. The dotted column corresponds to the atmosphere outside a stack or chimney. The difference in weights of the columns creates a pressure difference (AP) known as draft (see glossary), expressed in inches or millimeters of water column on a manometer. The draft is proportional to the height of the gas column and to the difference in densities of the hot and cold gas columns. The densities of air and other gases depend on their pressures and temperatures, thus density, p = p/RT, where density is pounds per cubic foot (US) or kg/m (SI), T is absolute temperature rankine (US) or kelvin (SI), and P is a constant = 53.3 fp/pound mol °R for air (US), or 287 joules-kg-mol °K for air (SI). Densities are tabulated in references 51 and 52. 

Methods—PycnomOric. Details for the accurate use of the pycnometer were outlined by Twight (1951). He stressed the necessity of an accurate calibration of the pycnometer and control of temperature. Rankine (1952) obtained results to +0.05% when proper attention was given to temperature control. He recommended use of a water bath set slightly above room temperature and pycnometers calibrated to the same temperature. Botelho (1939) preferred the pycnometer for the determination of alcohol. 

Re = Reynolds Number, dimensionless AP = Change in temperature Pavg = Average gas flowing temperature, Rankine Ti, = Base temperature, Rankine Pj Initial temperature of the gas, Rankine P2 = Temperature of the gas under the second conditions, Rankine Vi = Volume of the gas in original condition, fC V% — Volnme of the gas in second set of conditions, ft ... 

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