Properties of low-temperature spectral relaxation of eosin phosphorescence in a glycerol-water mixture

2000 ◽  
Vol 88 (3) ◽  
pp. 346-351 ◽  
Author(s):  
A. V. Pastukhov ◽  
V. R. Fogel’ ◽  
A. I. Kotel’nikov
Keyword(s):  
Low Temperature ◽  
Water Mixture ◽  
Glycerol Water ◽  
Spectral Relaxation

Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources, Part II: Experimental Investigation

2003 ◽  
Vol 125 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Gunnar Tamm ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperature ◽  
System Analysis ◽  
Waste Heat ◽  
Thermal Power ◽  
Experimental System ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Water Mixture ◽  
Theoretical Simulation

A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally, exhibiting expected trends, but with deviations from ideal and equilibrium modeling. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating conditions.

A Totally Heat-Driven Refrigeration System Using Low-Temperature Heat Sources for Low-Temperature Applications

2019 ◽  
Vol 27 (02) ◽  
pp. 1950012 ◽  
Author(s):  
Zeynab Seyfouri ◽  
Mehran Ameri ◽  
Mozaffar Ali Mehrabian
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
Refrigeration System ◽  
Power Requirement ◽  
Temperature Heat

In the present study, a totally heat-driven refrigeration system is proposed and thermodynamically analyzed. This system uses a low-temperature heat source such as geothermal energy or solar energy to produce cooling at freezing temperatures. The proposed system comprises a Rankine cycle (RC) and a hybrid GAX (HGAX) refrigeration cycle, in which the RC provides the power requirement of the HGAX cycle. An ammonia–water mixture is used in both RC and HGAX cycles as the working fluid. A comparative study is conducted in which the proposed system is compared with two other systems using GAX cycle and/or a single stage cycle, as the refrigeration cycle. The study shows that the proposed system is preferred to produce cooling at temperatures from 2∘C to [Formula: see text]C. A detailed parametric analysis of the proposed system is carried out. The results of the analysis show that the system can produce cooling at [Formula: see text]C using a low-temperature heat source at 133.5∘C with the exergy efficiency of about 20% without any input power. By increasing the heat source temperature to 160∘C, an exergy efficiency of 25% can be achieved.

A Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources: Part II — Experimental Investigation

Solar Energy ◽  
2002 ◽  
Author(s):  
Gunmar Tamm ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperature ◽  
System Analysis ◽  
Waste Heat ◽  
Thermal Power ◽  
Experimental System ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Water Mixture ◽  
Theoretical Simulation ◽  
Intensive Investigation

A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or an independent cycle using low temperature sources such as geothermal and solar energy. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally, exhibiting expected trends, but with deviations from ideal and equilibrium modeling. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating parameters.

HYDROTHERMAL SYNTHESIS OF CALCIUM HYDROSILICATES

1934 ◽  
Vol 11 (4) ◽  
pp. 520-529 ◽  
Author(s):  
V. A. Vigfusson ◽  
G. N. Bates ◽  
T. Thorvaldson
Keyword(s):  
Hydrothermal Synthesis ◽  
Silica Gel ◽  
Fused Silica ◽  
Steam Treatment ◽  
Crystalline Substance ◽  
Water Mixture ◽  
Glycerol Water ◽  
X Ray ◽  
Lime Water ◽  
Calcium Hydrosilicate

A crystalline substance which appears in steam-cured Portland cement mortar has been shown to be a calcium hydrosilicate and has been prepared by hydrothermal synthesis from mixtures of silica sand with lime, dicalcium silicate and tricalcium silicate, silica gel and lime (after preliminary steam treatment and ignition) and by the action of saturated lime water on quartz crystals or fused silica plates. The crystals appear not to be acted on by solutions of sodium sulphate, calcium sulphate or alkali hydroxides, but they are slowly decomposed by solutions of magnesium sulphate and alkali carbonates and rapidly by dilute acids and ammonium salts. The crystals were obtained free from amorphous matter by growing them on quartz or silica plates in saturated lime water. When the compound was prepared in this way, the lime-silica-water ratio was found to be 2:1:1, the formula being therefore 2CaO∙SiO2∙H2O or H2Ca2SiO5. This product usually appears as thin lath-like prisms showing parallel extinction, positive elongation and moderate birefringence. The crystals are optically positive with a fairly large optic angle. 2V = 68°. The indices of refraction are αNa = 1.614 ±.002, βNa = 1.620 ±.002, γNa = 1.633 ±.002. The optical plane is parallel to the macropinacoid (100) and the acute bisectrix Z is parallel to the direction of elongation which is taken as the crystallographic axis C. The optical properties and X-ray pattern are distinctive and entirely different from those of hillebrandite or foshagite, which have the same composition.Another crystalline calcium hydrosilicate was obtained by hydrothermal synthesis from excess lime and silica gel. This appeared as very small needle-like prisms, observable only when magnified about 200 times. The crystals show parallel extinction, positive elongation and very low birefringence with an index of refraction of 1.597 ±.003. Analysis of this product, extracted with a glycerol-water mixture to remove excess lime, gave a lime-silica ratio of 2 to 1 with an uncertain amount of water of at least one mole. The X-ray pattern is distinctive and shows only slight similarity to the hillebrandite pattern.

Performance Improvement of a Combined Power and Cooling Cycle for Low Temperature Heat Sources Using Internal Heat Recovery and Scroll Expander

2019 ◽  
Author(s):  
Martina Leveni ◽  
Arun Kumar Narasimhan ◽  
Eydhah Almatrafi ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperature ◽  
Heat Recovery ◽  
Pressure Ratio ◽  
Internal Heat ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Water Mixture ◽  
Heat Sources ◽  
Scroll Expander ◽  
Temperature Heat

Abstract Low temperature heat sources inherently result in lower cycle efficiencies, which can be improved by means of combined power and cooling generation. In order to produce power and cooling, appropriate thermodynamic cycles and working fluids must be used. Goswami cycle is a combined cycle that produces power and refrigeration by using ammonia-water mixture for low temperature heat sources. In the present study, a scroll expander is modeled specifically for the cycle operating conditions and a theoretical investigation is conducted to determine the cycle performance. A scroll expander design suitable for the operating conditions improves the power output and thereby overall thermal efficiency. The scroll expander efficiency varied between 0.05 and 0.61 for the pressure ratio between 2.2 and 8.6, with a maximum efficiency of 0.697 achieved at a pressure ratio of about 4.4. An internal heat recovery from the rectifier is proposed along with a flow split in the strong solution and analyzed for overall cycle energy efficiency improvement. Internal heat recovery from the rectifier increased the first law effective efficiency and the effective exergy efficiency by 7.9% and 7.8%, respectively, over the basic configuration.

Experimental and CFD Investigations of Heat Transfer in Helical Coils for the Development of Correlations for Newtonian and Non-Newtonian Fluids in Transient State-Space Conditions

2013 ◽  
Author(s):  
Sandipan S. Pawar ◽  
Vivek K. Sunnapwar ◽  
Vivek K. Yakkundi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Turbulent Flow ◽  
Transfer Coefficient ◽  
Flow Regimes ◽  
Newtonian Fluids ◽  
Water Mixture ◽  
Glycerol Water ◽  
Laminar And Turbulent Flow ◽  
Helical Coils

Experimental studies and CFD investigations were carried out under laminar and turbulent flow regimes in isothermal steady state and non-isothermal unsteady state conditions in helical coils for Newtonian and non-Newtonian fluids. Water and glycerol-water mixture (10 and 20 % glycerol) as Newtonian fluids and dilute aqueous polymer solutions of sodium carboxymethyl cellulose (SCMC), sodium alginate (SA) as non-Newtonian fluids were used in this study. The experiments were performed for three helical coils of coil curvature ratios as 0.0757, 0.064 and 0.055 in laminar and turbulent flow regimes. For the first time, two innovative correlations to calculate Nusselt number (Nu) in terms of new dimensionless ‘M’ number, Prandtl number and coil curvature ratio under different conditions for Newtonian fluids are proposed in this paper. Third correlation of Nu vs. Graetz number (Gz) including the effects of coil curvature on heat transfer coefficient which was not considered by earlier investigators is developed based on tests conducted in laminar flow for Newtonian fluids. All these three innovative correlations developed based on experimental data which were not found in the literature. These correlations were compared with the work of earlier investigators and were found to be in good agreement. The CFD analysis for laminar and turbulent flow was carried out using the CFD package FLUENT 12.0.16. The CFD calculation results (Nui, U) for laminar and turbulent flows were compared with the experimental results, and also the work of earlier investigators was found to be in excellent agreement. Further, the effect of helix diameter on heat transfer for Newtonian and Non-Newtonian fluids are also presented in this paper and it was observed that as helix diameter increases, overall heat transfer coefficient decreases.

Preference for Isolated Water Molecules in a Concentrated Glycerol–Water Mixture

2011 ◽  
Vol 115 (24) ◽  
pp. 7799-7807 ◽  
Author(s):  
J. J. Towey ◽  
A. K. Soper ◽  
L. Dougan
Keyword(s):  
Water Molecules ◽  
Water Mixture ◽  
Glycerol Water
Sign in / Sign up

Export Citation Format

Share Document