scholarly journals Performance of an Intermittent Absorption Cycle refrigerator Producing Continuous Cooling Effect.(Dept.M)

2021 ◽  
Vol 12 (1) ◽  
pp. 34-42
Author(s):  
Helmy El-Sayed Gad ◽  
A. Hamed
2019 ◽  
Vol 17 (2) ◽  
pp. 69
Author(s):  
Afdhal Kurniawan Mainil ◽  
Sarwo Fikri ◽  
Azridjal Aziz

Mesin pengkondisian udara umumnya digunakan untuk memberikan efek pendinginan (cooling effect). Efek pendinginan dimaksudkan untuk memberikan kenyamanan di ruang yang didinginkan, sehingga rasa nyaman membuat orang betah didalamnya. Mesin pengkondisian udara secara termodinamika kebanyakan beroperasi menggunakan siklus kompresi uap, dimana panas diserapkan disisi evaporator di dalam ruangan, kemudian panas tersebut dibuang di kondensor di luar ruangan. Proses tersebut dapat berlangsung karena kerja kompresor dan penurunan tekanan yang terjadi pada katup ekpansi atau pipa kapiler, sehingga siklus kompresi uap bekerja sempurna. Pada sistem pengkondisian udara biasanya panas terbuang kelingkungan begitu saja, panas tersebut dapat dimanfaatkan untuk memanaskan air dengan penambahan kondensor dummy. Penambahan kondensor dummy pada penelitian ini dilakukan untuk melihat pengaruh penambahan kondensor dummy terhadap beban pendingin, daya kompresi, temperatur, dan Coefficient of Performance (COP). Metode yang digunakan pada penelitian ini ialah metode rancang bangun dan eksperimental. Berdasarkan hasil pengujian, selama pengoperasian 120 menit diperoleh temperatur air panas pada  kondisi tanpa beban (0W), beban 1000W, 2000W dan 3000W berturut-turut adalah 52,83oC, 56,58oC, 57,93oC dan 64,73oC.


2021 ◽  
Vol 13 (3) ◽  
pp. 1537
Author(s):  
Irene Zluwa ◽  
Ulrike Pitha

In the case of building surfaces, the installation of green roofs or green facades can be used to reduce the temperature of the environment and the building. In addition, introducing photovoltaic energy production will help to reduce CO2 emissions. Both approaches (building greenery and photovoltaic energy production) compete, as both of them are located on the exterior of buildings. This paper aims to give an overview of solutions for the combination of building greenery (BG) systems and photovoltaic (PV) panels. Planning principles for different applications are outlined in a guideline for planning a sustainable surface on contemporary buildings. A comprehensive literature review was done. Identified solutions of combinations were systematically analysed and discussed in comparison with additional relevant literature. The main findings of this paper were: (A) BG and PV systems with low sub-construction heights require shallow substrates/low growing plants, whereas in the case of the combination of (a semi)-intensive GR system, a distance of a minimum 60 cm between the substrate surface and lower panel edge is recommended; (B) The cooling effect of the greenery depends on the distance between the PV and the air velocity; (C) if the substrate is dry, there is no evapotranspiration and therefore no cooling effect; (D) A spectrum of different PV systems, sub-constructions, and plants for the combination of BG and PV is necessary and suitable for different applications shown within the publication.


2021 ◽  
Vol 52 (7) ◽  
pp. 3122-3139
Author(s):  
Nicholas J. Krutz ◽  
Chen Shen ◽  
Carolin Fink ◽  
Jiashi Miao ◽  
Timothy Hanlon ◽  
...  

2021 ◽  
Vol 14 (1) ◽  
pp. 151-157
Author(s):  
Marlena Lembicz ◽  
Zbigniew Miszalski ◽  
Andrzej Kornaś ◽  
Katarzyna Turnau
Keyword(s):  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianlong Chang ◽  
Xinlei Duan ◽  
Yang Du ◽  
Baoquan Guo ◽  
Yutian Pan

AbstractBy combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.


Author(s):  
Jyrki Miettinen ◽  
Sami Koskenniska ◽  
Mahesh Somani ◽  
Seppo Louhenkilpi ◽  
Aarne Pohjonen ◽  
...  

AbstractNew continuous cooling transformation (CCT) equations have been optimized to calculate the start temperatures and critical cooling rates of phase formations during austenite decomposition in low-alloyed steels. Experimental CCT data from the literature were used for applying the recently developed method of calculating the grain boundary soluble compositions of the steels for optimization. These compositions, which are influenced by solute microsegregation and precipitation depending on the heating/cooling/holding process, are expected to control the start of the austenite decomposition, if initiated at the grain boundaries. The current optimization was carried out rigorously for an extended set of steels than used previously, besides including three new solute elements, Al, Cu and B, in the CCT-equations. The validity of the equations was, therefore, boosted not only due to the inclusion of new elements, but also due to the addition of more low-alloyed steels in the optimization. The final optimization was made with a mini-tab tool, which discarded statistically insignificant parameters from the equations and made them prudently safer to use. Using a thermodynamic-kinetic software, IDS, the new equations were further validated using new experimental CCT data measured in this study. The agreement is good both for the phase transformation start temperatures as well as the final phase fractions. In addition, IDS simulations were carried out to construct the CCT diagrams and the final phase fraction diagrams for 17 steels and two cast irons, in order to outline the influence of solute elements on the calculations and their relationship with literature recommendations.


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