1,721,101 research outputs found
Issue 5: Building Simulation
No full textSome of the works presented at BSA 2017 have been invited to appear as extended papers in this special issue, together with some additional contributions relevant to the topic
Chemical dehumidification of air by liquid desiccant: desiccant regeneration in a packed column with structured and random packing
No full textThis paper presents the experimental tests on desiccant regeneration carried out in a packed column with the hygroscopic solution H2O/LiBr. Two different packed columns were tested: random packing consisting of 1” Pall Ring elements and an ordinate column MELLAPACK 250Y.
The experimental results are reported in terms of desiccant concentration increase, air side pressure drop and regeneration effectiveness. The experimental tests show that desiccant regeneration requires a temperature level around 40-50°C which can be easily obtained by using solar energy or heat recovered from an industrial process or from a thermal engine. The random packing shows higher regeneration performances, whereas the structured packing shows lower air side pressure drop.
The experimental results are also compared against a one-dimensional simulation code of a packed column: a fair agreement is found between experiments and simulation
Heat transfer and pressure drop during HFC refrigerant vaporisation inside a brazed plate heat exchanger
No full textThis paper presents the experimental heat transfer coefficients and pressure drop measured during HFC refrigerant 134a, 410A and 236fa vaporisation inside a small brazed plate heat exchanger: the effects of heat flux, refrigerant mass flux, saturation temperature, outlet conditions and fluid properties are investigated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure drop. The heat transfer coefficients show great sensitivity to heat flux and outlet conditions and weak sensitivity to saturation temperature. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow. HFC-410A shows heat transfer coefficients 40–50% higher than HFC-134a and 50–60% higher than HFC-236fa and frictional pressure drops 40–50% lower than HFC-134a and 50–60% lower than HFC-236fa. The experimental heat transfer coefficients are compared with two well-known equations for nucleate boiling [M.G. Cooper, Heat flows rates in saturated pool boiling – a wide ranging examination using reduced properties, Advanced Heat Transfer, Academic Press, Orlando, Florida, 1984, pp. 157–239; D. Gorenflo, Pool boiling, in: E.U. Schlu ̈nder (Ed.), VDI Heat Atlas, Dusseldorf, Germany, 1993, Ha1-25] and a correlation for frictional pressure drop is proposed
Comparaison entre differents systemes de recuperation de chaleur sensible et latente sur l’air rejete, Revue General du Froid, 2005, n.1056, p.41-46
No full textExperimental heat transfer coefficients and pressure drop during refrigerant R-134a vaporisation inside a commercial brazed plate heat exchanger
No full textThis paper presents the experimental heat transfer coefficients and pressure drop measured during refrigerant R-134a vaporisation inside a commercial brazed plate heat exchanger (BPHE). The BPHE tested consists of 10 plates 72 mm in width and 310 mm in length, which present a macro-scale herringbone corrugation with inclination angle around 65° and corrugation amplitude of 2 mm. The experimental set-up is fully described together with measurements, procedures, data reduction and accuracy. The effects of heat flux, refrigerant mass flux and pressure are investigated. The experimental heat transfer coefficients are compared against semi-empirical correlation
HFC-410A vaporisation inside a commercial brazed plate heat exchanger
No full textThis paper experimentally investigates HFC-410A vaporisation inside a commercial brazed plate heat exchanger: the effects of heat flux, refrigerant mass flux, saturation temperature and outlet conditions are evaluated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure drop. The heat transfer coefficients show great sensitivity to heat flux and outlet conditions and weak sensitivity to saturation temperature. 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. The experimental heat transfer coefficients are compared with two well-known equations [Cooper, M.G., Heat flows rates in saturated pool boiling – a wide ranging examination using reduced properties, in: J.P. Hartnett, T.F. Irvine Jr. (Eds.), Advanced in Heat Transfer, Academic Press, Orlando, FL, 1984, pp. 157–239; D. Gorenflo, D. Pool boiling, in: E.U. Schlu ̈nder (Ed.), VDI Heat Atlas, Dusseldorf, Germany, 1993 (Ha1-25).] for nucleate boiling and a correlation for frictional pressure drop is proposed
Heat transfer and pressure drop during HFC-134a condensation inside a commercial brazed plate heat exchanger
No full textThis paper presents the experimental tests on HFC-134a condensation inside a commercial brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature and vapour super-heating are investigated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure drop.
At low refrigerant mass flux ( 20 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 30% increase for a doubling of the refrigerant mass flux. The condensation heat transfer coefficients of super-heated vapour are 8 - 10% higher than those of saturated vapour. The heat transfer coefficients show weak sensitivity to saturation temperature.
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
Experimental analysis on desiccant regeneration in a packed column with structured and random packing
No full textThis paper presents the experimental tests on desiccant regeneration carried out in a packed column with the hygroscopic solution H2O/LiBr. Two different packed columns have been tested: a random column consisting of 1” Pall Ring elements and a structured column Mellapack 250Y. The experimental results are reported in terms of desiccant concentration increase, regeneration effectiveness and air side pressure drop. The experimental tests show that desiccant regeneration requires a temperature level around 50°C that can be easily obtained by using solar energy or heat recovered from an industrial process or from a thermal engine. The random column shows regeneration performance 20-25% higher than structured column, whereas the structured column shows air side pressure drop from 65 to 75% lower. The experimental results have been compared against a one-dimensional simulation code of a packed column: a fair agreement is found between experiments and simulation
Refrigerant R134a vaporisation heat transfer and pressure drop inside a small brazed plate heat exchanger
No full textThis paper presents the experimental heat transfer coefficients and pressure drop measured during refrigerant R134a vaporisation inside a small brazed plate heat exchanger (BPHE): the effects of heat flux, refrigerant mass flux, saturation temperature and outlet conditions are investigated. The BPHE tested consists of 10 plates, 72 mm in width and 310 mm in length, which present a macro-scale herringbone corrugation with an inclination angle of 65° and corrugation amplitude of 2 mm. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure drop. The heat transfer coefficients show great sensitivity both to heat flux and outlet conditions and weak sensitivity to saturation temperature. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow. The experimental heat transfer coefficients are also compared with two well-known correlations for nucleate pool boiling and a correlation for frictional pressure drop is proposed
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