scholarly journals Thermal Assessment of Selective Solar Troughs

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3130
Author(s):  
Shahzada Zaman Shuja ◽  
Bekir Sami Yilbas ◽  
Hussain Al-Qahtani
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Working Fluid ◽  
Second Law ◽  
Inlet Temperature ◽  
Pressurized Water ◽  
Pressure Drops ◽  
Fluid Mass

A comparative study was carried out incorporating a novel approach for thermal performance evaluations of commonly used parabolic trough collectors, namely the Euro, Sky, and Helio troughs. In the analysis, pressurized water and therminol-VP1 (eutectic mixture of diphenyl oxide (DPO) and biphenyl) fluid were introduced as working fluids, and the governing equation of energy was simulated for various working fluid mass flow rates and inlet temperatures. The thermal performance of the troughs was assessed by incorporating the first- and second-law efficiencies and by using temperature increases and pressure drops of the working fluid. It was found that the first-law efficiency of the troughs increased with the working fluid mass flow rate, while it decreased with an increasing working fluid inlet temperature. The first-law efficiency remained the highest for the Euro trough, followed by the Sky and Helio troughs. The second-law efficiency reduced with an increasing working fluid mass flow rate, while it increased with an increasing working fluid inlet temperature. The second-law efficiency became the highest for the Helio Trough, followed by the Sky and Euro troughs. The temperature increase remained the highest along the length of the receiver for the Helio Trough compared to that corresponding to the Euro and Sky troughs for the same mass flow rate of the working fluid. The pressure drops in the working fluid became high for the Euro Trough, followed by the Sky and Helio troughs. The pressurized water resulted in higher second-law efficiency than the therminol-VP1 fluid did for all of the troughs considered.

Dynamic Behavior and Off-Design Performance Analysis of Solar Driven ORC Using Scroll Expanders

2019 ◽  
Author(s):  
Ying Zhang ◽  
Arun Kumar Narasimhan ◽  
Mengjie Bai ◽  
Li Zhao ◽  
Shuai Deng ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
System Level ◽  
Working Fluid ◽  
Small Scale ◽  
Solar Insolation ◽  
Design Performance ◽  
Fluid Mass

Abstract Solar driven ORC system is a possible solution for small-scale power generation. A scroll expander is considered due to its better suitability among other positive displacement expanders for small-scale power outputs. This work conducted a test of an ORC system with an expansion valve by varying the working fluid mass flow rate in two scenarios. A dynamic system-level model of ORC was developed and validated with experimental data. The validated model was used to predict the ORC performance considering off-design conditions of expander and solar insolation. The experimental data showed that pressures and temperatures exhibited the same trend as that of the working fluid mass flow rate, of which the evaporation pressure was the most sensitive to this variation. The simulation results are in good agreement with the experimental results. Results from the dynamic model showed that the ORC power output was underestimated by up to 54.7%, when off-design performance of expander was not considered. Considering the expander off-design performance and solar insolation, a highest thermal efficiency of 7.6% and an expander isentropic efficiency of 80.6% were achieved.

The Performance of a Novel Solar Cooling and Power System with Different Working Fluids

2014 ◽  
Vol 672-674 ◽  
pp. 86-93 ◽  
Author(s):  
Huan Lei ◽  
Jin Fu Yang ◽  
Dong Jiang Han
Keyword(s):  
Power System ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Supply And Demand ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Cooling Power ◽  
Working Fluids

Due to serious environmental problems and energy supply and demand issues, solar energy as a clean and abundant energy gets more and more attention. This paper presented a novel cooling and power system combined with PTCs. The system performance analysis was conducted with four different organic working fluids. The impacts of organic Rankine cycle (ORC) evaporation temperature, ORC condensing temperature and heat transfer fluid (HTF) mass flow rate in evaporator on system thermal performance were analyzed. The results show that system with toluene as working fluid has the highest thermal and exergy efficiency, and D4 and MDM have the lowest. Different working fluids have different cooling power to electricity ratios. The HTF mass flow rate in evaporator has a significant effect on system thermal performance.

scholarly journals Experimental Research of Dynamic Instabilities in the Presence of Coiled Wire Inserts on Two-Phase Flow

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Gokhan Omeroglu ◽  
Omer Comakli ◽  
Sendogan Karagoz ◽  
Bayram Sahin
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Density Wave ◽  
Working Fluid ◽  
Outer Side ◽  
Inlet Temperature ◽  
Two Phase ◽  
Flux Boundary Condition

The aim of this study is to experimentally investigate the effect of the coiled wire insertions on dynamic instabilities and to compare the results with the smooth tube for forced convection boiling. The experiments were conducted in a circular tube, and water was used as the working fluid. Two different pitch ratios (H/D=2.77and 5.55) of coiled wire with circular cross-sections were utilised. The constant heat flux boundary condition was applied to the outer side of the test tube, and the constant exit restriction was used at the tube outlet. The mass flow rate changed from 110 to 20 g/s in order to obtain a detailed idea about the density wave and pressure drop oscillations, and the range of the inlet temperature was 15–35°C. The changes in pressure drop, inlet temperature, amplitude, and the period with mass flow rate are presented. For each configuration, it is seen that density wave and pressure drop oscillations occur at all inlet temperatures. Analyses show that the decrease in the mass flow rate and inlet temperature causes the amplitude and the period of the density wave and the pressure drop oscillations to decrease separately.

scholarly journals Modelling an unconventional closed-loop deep borehole heat exchanger (DBHE): sensitivity analysis on the Newberry volcanic setting

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Hannah R. Doran ◽  
Theo Renaud ◽  
Gioia Falcone ◽  
Lehua Pan ◽  
Patrick G. Verdin
Keyword(s):  
Sensitivity Analysis ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Energy Flow ◽  
Closed Loop ◽  
Working Fluid ◽  
Valuable Insight ◽  
Deep Borehole

AbstractAlternative (unconventional) deep geothermal designs are needed to provide a secure and efficient geothermal energy supply. An in-depth sensitivity analysis was investigated considering a deep borehole closed-loop heat exchanger (DBHE) to overcome the current limitations of deep EGS. A T2Well/EOS1 model previously calibrated on an experimental DBHE in Hawaii was adapted to the current NWG 55-29 well at the Newberry volcano site in Central Oregon. A sensitivity analysis was carried out, including parameters such as the working fluid mass flow rate, the casing and cement thermal properties, and the wellbore radii dimensions. The results conclude the highest energy flow rate to be 1.5 MW, after an annulus radii increase and an imposed mass flow rate of 5 kg/s. At 3 kg/s, the DBHE yielded an energy flow rate a factor of 3.5 lower than the NWG 55-29 conventional design. Despite this loss, the sensitivity analysis allows an assessment of the key thermodynamics within the wellbore and provides a valuable insight into how heat is lost/gained throughout the system. This analysis was performed under the assumption of subcritical conditions, and could aid the development of unconventional designs within future EGS work like the Newberry Deep Drilling Project (NDDP). Requirements for further software development are briefly discussed, which would facilitate the modelling of unconventional geothermal wells in supercritical systems to support EGS projects that could extend to deeper depths.

Experimental Investigation of a Pilot Compression Chiller With Alternatives Refrigerants R401a and R134a

2005 ◽  
Author(s):  
M. Fatouh
Keyword(s):  
Experimental Investigation ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Inlet Temperature ◽  
Chilled Water ◽  
Water Mass Flow Rate

This paper reports the results of an experimental investigation on a pilot compression chiller (4 kW cooling capacity) working with R401a and R134a as R12 alternatives. Experiments are conducted on a single-stage vapor compression refrigeration system using water as a secondary working fluid through both evaporator and condenser. Influences of cooling water mass flow rate (170–1900 kg/h), cooling water inlet temperature (27–43°C) and chilled water mass flow rate (240–1150 kg/h) on performance characteristics of chillers are evaluated for R401a, R134a and R12. Increasing cooling water mass flow rate or decreasing its inlet temperature causes the operating pressures and electric input power to reduce while the cooling capacity and coefficient of performance (COP) to increase. Pressure ratio is inversely proportional while actual loads and COP are directly proportional to chilled water mass flow rate. The effect of cooling water inlet temperature, on the system performance, is more significant than the effects of cooling and chilled water mass flow rates. Comparison between R12, R134a and R401a under identical operating conditions revealed that R401a can be used as a drop-in refrigerant to replace R12 in water-cooled chillers.

scholarly journals Analytical and Experimental Investigation of a Plate Fin Heat Exchanger at Cryogenics Temperature

2021 ◽  
Vol 39 (4) ◽  
pp. 1225-1235
Author(s):  
Ajay K. Gupta ◽  
Manoj Kumar ◽  
Ranjit K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Cryogenic Temperature ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Compact Size

Plate-fin heat exchangers provide a broad range of applications in many cryogenic industries for liquefaction and separation of gasses because of their excellent technical advantages such as high effectiveness, compact size, etc. Correlations are available for the design of a plate-fin heat exchanger, but experimental investigations are few at cryogenic temperature. In the present study, a cryogenic heat exchanger test setup has been designed and fabricated to investigate the performance of plate-fin heat exchanger at cryogenic temperature. Major parameters (Colburn factor, Friction factor, etc.) that affect the performance of plate-fin heat exchangers are provided concisely. The effect of mass flow rate and inlet temperature on the effectiveness and pressure drop of the heat exchanger are investigated. It is observed that with an increase in mass flow rate effectiveness and pressure drop increases. The present setup emphasis the systematic procedure to perform the experiment based on cryogenic operating conditions and represent its uncertainties level.

scholarly journals An experimental study of the thermal performance of the square and rhombic solar collectors

2018 ◽  
Vol 22 (1 Part B) ◽  
pp. 487-494 ◽  
Author(s):  
Aminreza Noghrehabadi ◽  
Ebrahim Hajidavaloo ◽  
Mojtaba Moravej ◽  
Ali Esmailinasab
Keyword(s):  
Experimental Study ◽  
Flat Plate ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Performance ◽  
Thermal Efficiency ◽  
Solar Collectors ◽  
Heating Systems ◽  
Solar Water Heating

Solar collectors are the key part of solar water heating systems. The most widely produced solar collectors are flat plate solar collectors. In the present study, two types of flat plate collectors, namely square and rhombic collectors are experi?mentally tested and compared and the thermal performance of both collectors is investigated. The results show both collectors have the same performance around noon (?61%), but the rhombic collector has better performance in the morning and afternoon. The values for rhombic and square collectors are approximately 56.2% and 53.5% in the morning and 56.1% and 54% in the afternoon, respectively. The effect of flow rate is also studied. The thermal efficiency of rhombic and square flat plate collectors increases in proportion to the flow rate. The results indicated the rhombic collector had better performance in comparison with the square collector with respect to the mass-flow rate.

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