scholarly journals Calculating the load on the room cooling ceiling panel at convective heat gains

2020 ◽  
Vol 164 ◽  
pp. 02006
Author(s):  
Elena Malyavina ◽  
Alexander Lomakin
Keyword(s):  
Thermal Stability ◽  
Convective Heat ◽  
Convective Flow ◽  
Cooling System ◽  
Working Hours ◽  
Engineering Practice ◽  
Convective Heat Flux ◽  
Long Period ◽  
Radiant Cooling ◽  
Calculation Results

A well-known statement of the theory of thermal stability asserts that when a harmonically time-changing convective heat flux enters a room, it can only be assimilated by a radiant cooling system if the assimilating flow exceeds the perturbing convective flow in magnitude. However, in engineering practice, there are no purely radiant systems. Therefore, the article has considered a ceiling cooling panel as a room cooling system, the heat flow from which is of a radiant-convective nature. The convective heat access to the room is constant during the working hours from 9 a.m. to 6 p.m. The task of determining the load on the cooling system has been performed by calculations.. Herewith, the rooms of different internal thermal stability have been considered. According to the calculation results, it has been found that, since the amount of the heat gains remains constant for a long period of time, the process of the room cooling comes almost to a stationary state and does not depend on the room thermal stability with assimilated heat gains, the value of which in different options varied from 100 W to 1000 W. It has been found, that when the temperature difference between the panel surface and the surrounding surfaces increases, the proportion of the convective assimilating flow becomes bigger.

scholarly journals Effects of Substitution of Y with Yb and Ce on the Microstructures and Mechanical Properties of Mg88.5Zn5Y6.5

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Hongxin Liao ◽  
Taekyung Lee ◽  
Jiangfeng Song ◽  
Jonghyun Kim ◽  
Fusheng Pan
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Creep Resistance ◽  
Room Temperature ◽  
High Thermal Stability ◽  
Long Period ◽  
Microstructures And Mechanical Properties

The microstructures and mechanical properties of the Mg88.5Zn5Y6.5-XREX (RE = Yb and Ce, X = 0, 1.5, 3.0, and 4.5) (wt.%) alloys were investigated in the present study. Mg88.5Zn5Y6.5 is composed of three phases, namely, α-Mg, long-period stacking ordered (LPSO) phases, and intermetallic compounds. The content of the LPSO phases decreased with the addition of Ce and Yb, and no LPSO phases were detected in Mg88.5Zn5Y2.0Yb4.5. The alloys containing the LPSO phases possessed a stratified microstructure and exhibited excellent mechanical properties. Mg88.5Zn5Y5.0Ce1.5 exhibited the highest creep resistance and mechanical strength at both room temperature and 200 °C, owing to its suitable microstructure and high thermal stability. The yield strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature was 358 MPa. The ultimate tensile strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature and 200 °C was 453 MPa and 360 MPa, respectively.

Analytical modeling of a radiant cooling system for thermal performance analysis

2021 ◽  
Author(s):  
Arup Chandra Saha ◽  
Vikas Verma ◽  
Rahul Tarodiya ◽  
M.R. Mahboob ◽  
Rajesh Kumar
Keyword(s):  
Performance Analysis ◽  
Thermal Performance ◽  
Analytical Modeling ◽  
Cooling System ◽  
Radiant Cooling

Land Subsidence Prediction Method of Power Cables Pipe Jacking Based on the Peck Theory

2013 ◽  
Vol 634-638 ◽  
pp. 3721-3724
Author(s):  
Yuan Liang Zhang ◽  
Yi Hu Zhang
Keyword(s):  
Land Subsidence ◽  
Prediction Method ◽  
Dominant Factor ◽  
Engineering Practice ◽  
Foundation Settlement ◽  
Power Cables ◽  
Overhead Transmission Line ◽  
Allowable Range ◽  
Calculation Results ◽  
Range Calculation

Overhead transmission line and cable are generally used for across or crossing the railway, highways and rivers.For higher deformation requirement of operation of the railway and highway foundation settlement,to ensure that the cable through the process of foundation in regulating the allowable range, calculation and prediction of foundation settlement is specially necessary.Based on the Peck theory, the dominant factor in foundation settlement-strata loss calculation method is introduced supplemented with measured settlement observation records in this paper,which confirmes that the calculation results are replicab in engineering practice.

scholarly journals Thermal Comfort and Energy Analysis of a Hybrid Cooling System by Coupling Natural Ventilation with Radiant and Indirect Evaporative Cooling

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7825
Author(s):  
Pradeep Shakya ◽  
Gimson Ng ◽  
Xiaoli Zhou ◽  
Yew Wah Wong ◽  
Swapnil Dubey ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Hybrid System ◽  
Natural Ventilation ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Supply System ◽  
Hybrid Cooling ◽  
Air Supply ◽  
Radiant Cooling ◽  
Indirect Evaporative Cooling

A hybrid cooling system which combines natural ventilation with a radiant cooling system for a hot and humid climate was studied. Indirect evaporative cooling was used to produce chilled water at temperatures slightly higher than the dew point. With this hybrid system, the condensation issue on the panel surface of a chilled ceiling was overcome. A computational fluid dynamics (CFD) model was employed to determine the cooling load and the parameters required for thermal comfort analysis for this hybrid system in an office-sized, well-insulated test room. Upon closer investigation, it was found that the thermal comfort by the hybrid system was acceptable only in limited outdoor conditions. Therefore, the hybrid system with a secondary fresh air supply system was suggested. Furthermore, the energy consumptions of conventional all-air, radiant cooling, and hybrid systems including the secondary air supply system were compared under similar thermal comfort conditions. The predicted results indicated that the hybrid system saves up to 77% and 61% of primary energy when compared with all-air and radiant cooling systems, respectively, while maintaining similar thermal comfort.

scholarly journals Thermal and long period stability of series of V(V), V(IV) and V(III) complex with Schiff base ligands in solid state

2019 ◽  
Vol 4 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Janusz Szklarzewicz ◽  
Anna Jurowska ◽  
Maciej Hodorowicz ◽  
Ryszard Gryboś
Keyword(s):  
Thermal Stability ◽  
Schiff Base ◽  
Solid State ◽  
Physicochemical Properties ◽  
General Formula ◽  
Oxidation State ◽  
Magnetic Moment ◽  
Tridentate Ligand ◽  
Schiff Base Ligands ◽  
Long Period

The synthesis and physicochemical properties of three new complexes of vanadium at +5, +4 and +3 oxidation state are described and discussed. The octahedral surrounding of vanadium for V(III) complexes of [V(L1)(HL1)] general formula is filled with two ONO tridentate ligand L, for V(IV) one ONO ligand L, oxido ligand and 1,10-phenanthroline (phen) as a co-ligand are presented in complexes of [VO(L2)(phen)]. For V(V) the complexes of [VO2(L1)(solv)] type were formed. As ligands, the H2L Schiff bases were formed in reaction between 5-hydroxysalcylaldehyde and phenylacetic hydrazide (H2L1) and 3,5-dichlorosalicyaldehyde and 4-hydroxybenzhydrazide (L2). The magnetic moment measurements, in 8 year period, show, that V(III) complexes slowly oxidise to V(IV) with preservation of the nonoxido character of the complexes, while V(IV) complexes were found to be stable. The TG and SDTA measurements indicate, that thermal stability depends mainly on the oxidation state of vanadium. The less thermally stable are the V(V) complexes, while V(IV) and V(III) are stable up to ca. 200oC. In solution, at pH 2 (similar to that in human digestion system), again the V(IV) are the most stable, only at pH 7.0 V(III) complexes had higher stability. The most stable, thus best for pharmaceutical use, are V(IV) complexes.

scholarly journals Improving the performance of the air-cooling unit in the cooling system of a radar

2021 ◽  
Vol 2057 (1) ◽  
pp. 012004
Author(s):  
Yu A Borisov ◽  
V V Volkov-Muzilev ◽  
D A Kalashnikov ◽  
H S Khalife
Keyword(s):  
Heat Exchanger ◽  
Gas Flow ◽  
Cooling System ◽  
Experimental Studies ◽  
Air Cooling ◽  
Axial Fan ◽  
Gas Dynamic ◽  
Cooling Unit ◽  
Calculation Results ◽  
Axial Fans

Abstract The article discusses the issues of reducing the size of the cooling unit of the antenna of a radar station by improving the gas-dynamic processes occurring in the air-cooling unit. The results of the experimental studies of the gas flow in a plate-fin heat exchanger, being blown by one axial fan are presented. The feasibility of changing the number of axial fans for organizing a more uniform flow around the heat-exchange surfaces has been determined by calculation and theoretical methods. The calculation results are confirmed by experimental studies of the air flow in the segment of the heat exchanger, which is provided by a smaller fan.

Progress of the 40 MW-Class Advanced Humid Air Turbine Tests

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Manabu Yagi ◽  
Hidefumi Araki ◽  
Hisato Tagawa ◽  
Tomomi Koganezawa ◽  
Chihiro Myoren ◽  
...  
Keyword(s):  
Metal Surface ◽  
Control Method ◽  
Cooling System ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Test Facility ◽  
Humid Air ◽  
Air Turbine ◽  
Calculation Results ◽  
Flow Compressor

A 40 MW-class test facility has been constructed to verify practicability of applying the advanced humid air turbine (AHAT) system to a heavy-duty gas turbine. Verification tests have been carried out from January 2012, and interaction effects between the key components were established. First, water atomization cooling (WAC) was confirmed to contribute to both increased mass flow rate and pressure ratio for the axial-flow compressor. The good agreement between measured and calculated temperatures at the compressor discharge was also confirmed. These results demonstrated the accuracy of the developed prediction model for the WAC. Second, a control method that realized both flame stability and low nitrogen oxides (NOx) emissions was verified. Although the power output and air humidity were lower than the rated values, NOx concentration was about 10 ppm. Finally, a hybrid nozzle cooling system, which utilized both compressor discharged air and humid air, was developed and tested. The metal surface temperatures of the first stage nozzles were measured, and they were kept under the permissible metal temperature. The measured temperatures on the metal surface reasonably corresponded with calculation results.

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