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HC-290 (Propane) Vaporisation Inside a Brazed Plate Heat Exchanger
Full text linkThis paper presents the heat transfer coefficients measured during HC-290 (Propane) vaporisation inside a brazed plate heat exchanger: the effects of heat flux, saturation temperature (pressure) and outlet conditions are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to heat flux and outlet conditions. The saturated boiling experimental heat transfer coefficients are compared with two well-known equations for nucleate boiling (Cooper (1984) and Gorenflo (1993)). The mean absolute percentage deviation between experimental and calculated heat transfer coefficients is 26.9% and 16.6% for Cooper (1984) and Gorenflo (1993) equation respectively. The heat transfer measurement has been complemented with IR thermography in order to quantify the portion of the heat transfer surface affected by vapour super-heating
Heat Transfer and Pressure Drop During HC-600a (Isobutane) Condensation Inside a Brazed Plate Heat Exchanger
Full text linkThis paper presents the heat transfer coefficients and the pressure drop measured during HC-600a (Isobutane) condensation inside a brazed plate heat exchanger: the effects of saturation temperature, refrigerant mass flux and vapour super-heating are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low refrigerant mass flux ( 18 kg/m2s) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. The condensation heat transfer coefficients of super-heated vapour are from 3 to 8% higher than those of saturated vapour. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on the refrigerant mass flux
HFO1234yf vaporisation inside a brazed plate heat exchanger
No full textThis paper presents the experimental heat transfer coefficients measured during HFO1234yf vaporisation inside a small brazed plate heat exchanger (BPHE): the effects of heat flux, saturation temperature (pressure) and outlet conditions are investigated.
The experimental tests have been carried out at three different saturation temperatures (10, 15 and 20°C) and four different evaporator outlet conditions (vapour quality around 0.80 and 1.00, vapour super-heating around 5 and 10°C. The heat transfer coefficients show great sensitivity to heat flux and outlet conditions and weak sensitivity to saturation temperature (pressure). The saturated boiling experimental heat transfer coefficients are compared with two well-known equations for nucleate boiling, Cooper (1984) and Gorenflo (1993): the mean absolute percentage deviation between calculated and experimental data is 8.6 and 12.9% for Cooper and Gorenflo correlation respectively. HFO1234yf heat transfer coefficients are similar to those of HFC134a measured during vaporisation inside the same BPHE under the same operating conditions
Air vs. Rail transport for medium range trips: a new comprehensive model for passengers modal choice.
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Heat transfer and pressure drop during hydrocarbon refrigerant condensation inside a brazed plate heat exchanger
No full textThis paper presents the experimental heat transfer coefficients and pressure drop measured during HC-600a (Isobutane), HC-290 (Propane) and HC-1270 (Propylene) saturated vapour condensation inside a small commercial brazed plate heat exchanger (BPHE): the effects of refrigerant mass flux, saturation temperature (pressure) and fluid properties are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature (pressure) and great sensitivity to refrigerant mass flux and fluid properties. A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 15-18 kg/m2s. At low refrigerant mass flux (Gr 15-18 kg/m2s) the heat transfer coefficients depend on mass flux and are well predicted by the Akers et al. (1959) equation: forced convection condensation occurs. In the forced convection condensation region the heat transfer coefficients show a 35-40% enhancement for a 60% increase of the refrigerant mass flux. HC-1270 shows heat transfer coefficients 5% higher than HC-600a and 10-15% higher than HC-290. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on mass flux
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