scholarly journals Thermal Performance Analysis of the Charging/Discharging Process of a Shell and Horizontally Oriented Multi-Tube Latent Heat Storage System

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6193
Author(s):  
Mohamed Fadl ◽  
Philip Eames
Keyword(s):  
Latent Heat ◽  
Flow Rate ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Volume Flow Rate ◽  
Storage System ◽  
Volume Flow ◽  
Hot Water ◽  
Working Fluid ◽  
Heat Demand

In this study, the thermal performance of latent heat thermal energy storage system (LHTESS) prototype to be used in a range of thermal systems (e.g., solar water heating systems, space heating/domestic hot water applications) is designed, fabricated, and experimentally investigated. The thermal store comprised a novel horizontally oriented multitube heat exchanger in a rectangular tank (forming the shell) filled with 37.8 kg of phase change material (PCM) RT62HC with water as the working fluid. The assessment of thermal performance during charging (melting) and discharging (solidification) was conducted under controlled several operational conditions comprising the heat transfer fluid (HTF) volume flow rates and inlet temperatures. The experimental investigations reported are focused on evaluating the transient PCM average temperature distribution at different heights within the storage unit, charging/discharging time, instantaneous transient charging/discharging power, and the total cumulative thermal energy stored/released. From the experimental results, it is noticed that both melting/solidification time significantly decreased with increase HTF volume flow rate and that changing the HTF inlet temperature shows large impacts on charging time compared to changing the HTF volume flow rate. During the discharging process, the maximum power output was initially 4.48 kW for HTF volume flow rate of 1.7 L/min, decreasing to 1.0 kW after 52.3 min with 2.67 kWh of heat delivered. Based on application heat demand characteristics, required power levels and heat demand can be fulfilled by employing several stores in parallel or series.

Partial Admission, Axial Impulse Type Turbine Design and Partial Admission Radial Turbine Test for SCO2 Cycle

2017 ◽  
Author(s):  
Hyungki Shin ◽  
Junhyun Cho ◽  
Young-Jin Baik ◽  
Jongjae Cho ◽  
Chulwoo Roh ◽  
...  
Keyword(s):  
Axial Force ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Small Diameter ◽  
Volume Flow ◽  
Working Fluid ◽  
Rotating Speed ◽  
Turbo Generator ◽  
Partial Admission ◽  
Reduce Development Time

Power generation cycle — typically Brayton cycle — to use CO2 at supercritical state as working fluid have been researched many years because this cycle increase thermal efficiency of cycle and decrease turbomachinery size. But small turbomachinery make it difficult to develop proto type Supercritical Carbon dioxide (S-CO2) cycle equipment of lab scale size. KIER (Korea Institute of Energy Research) have been researched S-CO2 cycle since 2013. This paper is about 60kWe scale and sub-kWe class turbo generator development for applying to this S-CO2 cycle at the lab scale. A design concept of this turbo-generator is to use commercially available components so as to reduce development time and increase reliability. Major problem of SCO2 turbine is small volume flow rate and huge axial force. High density S-CO2 was referred as advantage of S-CO2 cycle because it make small turbomachinery possible. But this advantage was not valid in lab-scale cycles under 100kW because small amount volume flow rate means high rotating speed and too small diameter of turbine to manufacture it. Also, high inlet and outlet pressure make huge axial force. To solve these problem, KIER have attempt various turbines. In this paper, these attempts and results are presented and discussed.

scholarly journals Evaluation of thermal performance for natural and forced draft wet cooling tower

2019 ◽  
Vol 13 (4) ◽  
pp. 6007-6021 ◽  
Author(s):  
M. J. Al-Dulaimi ◽  
F. A. Kareem ◽  
F. A. Hamad
Keyword(s):  
Flow Rate ◽  
Thermal Performance ◽  
Cooling Tower ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Experimental Results ◽  
Water Volume ◽  
Axial Fan ◽  
Natural Draft ◽  
Forced Draft

This paper presents an experimental and numerical investigation of the thermal performance of natural draft wet cooling tower (NDWCT). The experimental investigation is carried out under natural draft condition and forced draft condition created by an axial fan. The operational parameters considered in this study are the thickness of the fill (10 and 20 cm), inlet water temperature (40, 45, and 50 °C) and inlet water volume flow rate (5.68, 7.75, and 9.46 L/min). The experimental results showed that the thermal performance is improved when the fans are used with the NDWCT. The temperature difference between inlet and outlet and effectiveness increase by 35% and 37.2%, respectively at fill thickness of 20 cm and water volume flow rate of 11.35 L/min. The temperature distribution of the air and the relative humidity were numerically simulated for both cases of natural and forced draft by employing the commercial CFD software ANSYS Fluent 15. The experimental and numerical results were validated with results from a previous work and showed a good agreement. The experimental results showed that the effectiveness increase by 22% and 30% for NDWCT and FDWCT respectively when in case of fill thickness 20 cm.

Plate Diffuser Performance in Spherical Tank Thermocline Storage System

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Fahad Khan ◽  
Brian J. Savilonis
Keyword(s):  
Flow Rate ◽  
Thermal Efficiency ◽  
Volume Flow Rate ◽  
Storage System ◽  
Water Desalination ◽  
Hot Water ◽  
Discharge Process ◽  
Water Tank ◽  
Dimensionless Numbers ◽  
Spherical Tank

Thermal energy storage (TES) systems that store sensible heat in liquid media require the use of storage tanks. Spherical tanks require less building material and insulation, which might reduce the overall cost of a TES system while providing structural rigidity. The current study investigates an optimized plate diffuser in a thermocline spherical tank storage system to possibly increase the discharge flow rate without disrupting the thermocline region and without reducing the tank thermal efficiency. For low temperature (10–90 °C heat storage applications), such as heating, ventilation, and air conditioning (HVAC) and thermal water desalination, storing hot water in a thermocline system can increase the system thermal efficiency by up to 40% when compared to a fully mixed water tank and reduce the installation cost by 30% compared to a two-tank system. This study examines using a spherical tank in a thermocline system for such applications. A computational fluid dynamic (CFD) study simulated the discharge process from a spherical storage tank thermocline water system. Thermocline thickness and temperature profile in the tank were numerically determined for Reynolds number, Re = 600 and Froude number, Fr = 1.2; results were then experimentally validated. A CFD parametric study with (500 < Re < 7500) and (0.5 < Fr < 3.3): (i) determined the influence of tank flow dimensionless numbers (Reynolds, Froude, Richardson, and Archimedes) on thermal efficiency and thermocline thickness, (ii) produced an equation to predict the tank thermal efficiency using flow dimensionless numbers, and (iii) estimated the thermocline region volume occupation as a percentage of the total volume. The study of an optimized plate diffuser produced an equation for thermal efficiency based on Re and Fr numbers and estimated a thermocline volume equal to 15% of total tank volume. Flow rate ramp up by a factor of 3 was possible after the thermocline region was formed without losing tank thermal efficiency.

Thermal Performance Intensification of Car Radiator using SiO2/Water and ZnO/Water Nanofluids

2021 ◽  
pp. 1-25
Author(s):  
Hussein Maghrabie ◽  
Hamouda Mousa
Keyword(s):  
Heat Transfer ◽  
Working Conditions ◽  
Flow Rate ◽  
Thermal Performance ◽  
Cooling System ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Coolant Temperature ◽  
Inlet Temperature ◽  
The Impact

Abstract Recent progress in nanotechnology has lead to a revolution in the automotive cooling system. In the present work, enhancement of car radiator thermal performance was investigated using different nanofluids named SiO2/water, ZnO/water nanofluids as cooling mediums. The present study mainly aims to investigate the impact of (5 wt.%) from SiO2 and ZnO nanoparticles (NPs) dispersed in water based on car radiator heat transfer with spherical and hexagonal morphology, respectively. The experiments were performed in two working conditions of the nanofluids i.e coolant temperature and volume flow rate, moreover the present results were compared with the previous studies. The experimental working conditions were set at coolant inlet temperature (tc,i) ranged from 45 oC to 80 oC and the coolant volume flow rate (V) ranged from 3.5 lit/min to 6.5 lit/min. The experimental results show that the hexagonal ZnO/water nanofluid was superior towards enhancement of car radiator thermal performance comparing to that of SiO2 NPs. Additionally, at 6.5 lit/min and 45 °C, the enhancements of car radiator effectiveness due to using SiO2 and ZnO based water nanofluids and compared with that for the based water were 13.9% and 16%, respectively. The present study used the multiple regression analysis (MRA) and hence empirical correlations are suggested to estimate the overall heat transfer coefficient (U) for all coolants as functions of volume flow rate (V) and the coolant inlet temperature (tc,i) with a maximum STDEV of ± 1.85%.

Experimental Study of Thermal Energy Storage in Solar System Using PCM

2012 ◽  
Vol 433-440 ◽  
pp. 1027-1032 ◽  
Author(s):  
B. Kanimozhi ◽  
B.R. Ramesh Bapu
Keyword(s):  
Energy Storage ◽  
Solar Energy ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage System ◽  
Hot Water ◽  
Copper Tube

This paper summary the investigation and analysis of thermal energy storage extracted from solar heater and use for domestic purpose. Choosing a suitable phase change materials paraffin wax used for storing thermal energy in insulation tank. The tank carries minimum of 45 liters capacity of water and 50 numbers copper tubes each copper tube carries minimum of 100 grams PCM materials. Inside the tank phase change materials are receiving hot water from solar panel. This solar energy is stored in Copper tubes each copper tube contains PCM Materials as latent heat energy. Latent heat is absorbed and stored in Copper tubes .Large quantity of solar energy can be stored in a day time and same heat can be retrieved for later use. The tank was instrumented to measure inlet and outlet water temperature. The differences of temperature of the water is measured in a definite interval of time have been noted then calculating heat transfer rate and system effectiveness. The heat storage system is to be applied to store solar energy and the stored heat is used for domestic hot water supply system.

The Numerical Investigation of a New Passive Micromixer With Improved Tesla Structure

2009 ◽  
Author(s):  
YanFeng Fan ◽  
Ibrahim Hassan
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Cell Number ◽  
Side Branch ◽  
Volume Flow ◽  
Main Flow ◽  
Working Fluid ◽  
Mixing Efficiency ◽  
Gap Ratio ◽  
Passive Micromixer

In this paper, 3D numerical simulations are performed to investigate the mixing process within an improved Tesla micromixer. This improved Tesla micromixer applies the flow separation/recombination and converging/diverging principles to enhance mixing. A portion of the working fluid, which separates from the main flow, enters the Tesla side branch and mixes with the main flow again at the exit of the Tesla unit. The tested volume flow rate ranges from 1 μL/min to 100 μL/min. Grid independence is carried out to minimize the effect of numerical diffusion. Optimization is done to determine three parameters, which are the gap ratio (H/W), the mixing cell number (N), and the angle at the gap inlet (β). The effects of these three parameters on mixing are investigated at a volume flow rate of 100 μL/min. The simulation results show that the gap ratio is the most important factor. Three parameters are selected as H/W = 50/200, N = 10 and β = 90° for further investigation. The traditional Tesla micromixer is also simulated for comparison with the present design. The mixing efficiency is approximately 60% in the range of the tested volume flow rate. The improved micromixer has better mixing efficiency than the traditional Tesla micromixer when the volume flow rate is less than 50 μL/min.

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