scholarly journals Caloric method for the energetic evaluation of decentralised domestic ventilation devices

2019 ◽  
Vol 111 ◽  
pp. 01015
Author(s):  
Christian Friebe ◽  
Andreas Hantsch ◽  
Sabine Döge ◽  
Ralph Krause
Keyword(s):  
Heat Recovery ◽  
Test Bench ◽  
Electrical Heating ◽  
Change Rate ◽  
Home Ventilation ◽  
Temperature Change Rate ◽  
Flow Heat ◽  
Characteristic Values ◽  
Further Development ◽  
Reproducible Characteristic

In the context of this article, a caloric method for measuring the performance of alternating home ventilation devices (push-pull units) is presented. The simple and robust method provides both reliable and reproducible characteristic values. Based on this method, a test bench was developed and built. With this test bench the characteristic values (volume flow, heat recovery rate, temperature change rate) of series products can be measured. The aim of the investigation is the determination and evaluation of the possible parameters influencing the measurement. For this purpose, the parameters are illustrated on the basis of measured values from a defined test standard, consisting of a fan and electrical heating in a housing (so-called golden sample), as well as a pair of push-pull devices. As a result, suggestions for improvements to the previous procedure as well as approaches for further development are shown.

scholarly journals Model Experimental Study of Carbon Fiber Heating Wire for Deicing and Snow Melting on a Bridge Deck

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yan Tan ◽  
Yuntao Zhu ◽  
Henglin Xiao
Keyword(s):  
Surface Layer ◽  
Carbon Fiber ◽  
Temperature Change ◽  
Temperature Rise ◽  
Bridge Deck ◽  
Ice Melting ◽  
Snow Melting ◽  
Change Rate ◽  
Temperature Change Rate ◽  
Heating Wire

In order to use the carbon fiber heating wire more efficiently and safely, the influence of the built-in carbon fiber heating wires (CFHWs) on the temperature changes of the bridge deck is studied in this paper. The model experiments of the temperature rise and ice melting are carried out in a room with low temperature cold storage environment, and the temperature variation of the specimens under different ambient temperatures, namely, −2, −4, and −8°C, was measured. The results show that, in the temperature rise experiment, the temperature change rate of the measuring points of the surface layer in the central part above CFHW is the most obvious, with the temperature change rate of 2.123°C/h; owing to the limited radiation range of CFHW, the temperature change rate of the measuring points between the CFHW and the CFHW of the surface layer decreases significantly, with a value of 0.703°C/h, and the temperature of the measuring points of the heating layer where CFHW is located shows a nearly linear increase, with a temperature change rate of 1.313°C/h. The temperature of the bridge deck is basically above 0°C as most of the heat generated by CFHW is transferred to the bridge deck after heating, which can effectively prevent the bridge deck from freezing. In the ice melting experiment, the temperature change rate of the measuring points of the surface layer in the central part above the CFHW is 1.406°C/h, and the maximum temperature change rate of the measuring points between the CFHW and CFHW of the surface layer is 0.408°C/h. The overall ice melting condition on the specimen surface is appreciable. When the heating power is set to 190 W/m2, the influence of the ambient temperature on the measuring points of the surface layer is negligible, but the influence of the ice melting rate at different positions from the heating wire is obvious. Therefore, it can be seen that optimizing the layout of the CFHW can effectively improve the whole uniformity and efficiency of ice melting of the bridge deck. The results from relevant research can provide a reference for the design and operation of deicing and snow melting applications on a bridge deck.

scholarly journals RESEARCH OF THE ANGULAR POSITIONING ACCURACY OF THE EXPERIMENTAL TEST BENCH

2012 ◽  
Vol 32 (2) ◽  
pp. 37-41
Author(s):  
Vytautas Giniotis ◽  
Domantas Bručas
Keyword(s):  
Test Bench ◽  
Building Structure ◽  
Test Rig ◽  
Statistical Parameters ◽  
Positioning Accuracy ◽  
Angular Scale ◽  
Angular Measurements ◽  
Preliminary Research ◽  
Further Development ◽  
Experimental Test Bench

Most geodetic instruments are based on measurement of angular values. Such instruments as digital theodolites, total stations etc are used in geodesy, building structure, surveying, in machine engineering etc. Preliminary research of the accuracy of the test rig created for precise angular measurements is presented here. Visual angular scale accuracy measurements are given and some statistical parameters of measuring data are evaluated. Conclusions for further development of the test rig are formulated.

scholarly journals Experimental study of superheating of tin powders

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Han Gil Na ◽  
Youngmin Byoun ◽  
Suyoung Park ◽  
Myung Sik Choi ◽  
Changhyun Jin
Keyword(s):  
Experimental Study ◽  
Total Energy ◽  
Heating Rate ◽  
Entropy Change ◽  
Hysteresis Curve ◽  
Melting Points ◽  
Change Rate ◽  
Temperature Change Rate ◽  
The Difference ◽  
Scientific Engineering

Abstract An unstable energy-unbalanced state such as superheating or supercooling is often unexpectedly observed because a factor of energy depends not only on the temperature but is a product of temperature (T) and entropy (S). Thus, at the same temperature, if the entropy is different, the total energy of the system can be different. In such cases, the temperature-change-rate cannot match the entropy-change-rate, which results in a hysteresis curve for the temperature/entropy relationship. Due to the difference between the temperature- and entropy-change-rates, properties of a material, such as the boiling and freezing points, can be extended from point to area. This study confirmed that depending on the heating rate, tin powders exhibit different melting points. Given the contemporary reinterpretation of many energy-non-equilibrium phenomena that have only been discussed on the basis of temperature, this study is expected to contribute to the actual expansion of scientific/engineering applications.

Automated serial dilutions for high-dynamic-range assays enabled by fill-level-coupled valving in centrifugal microfluidics

Lab on a Chip ◽  
2019 ◽  
Vol 19 (13) ◽  
pp. 2205-2219 ◽  
Author(s):  
Peter Juelg ◽  
Mara Specht ◽  
Elena Kipf ◽  
Michael Lehnert ◽  
Cornelia Eckert ◽  
...  
Keyword(s):  
Temperature Change ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Centrifugal Microfluidics ◽  
Microfluidic Platforms ◽  
Change Rate ◽  
Temperature Change Rate ◽  
High Dynamic ◽  
Fill Level ◽  
Serial Dilutions

Time-independent, serial valving under rotation on centrifugal microfluidic platforms by a fill-level-coupled temperature change rate (FLC-TCR) actuated principle.

Heat Transfer Properties and Energy-Exergy Efficiency in a Finned Cross-Flow Heat Recovery Unit

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Isak Kotcioglu ◽  
Ahmet Cansiz
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Cross Flow ◽  
Exergy Loss ◽  
Entropy Generation Number ◽  
Recovery Unit ◽  
Transfer Unit ◽  
Flow Heat ◽  
Inlet Conditions ◽  
Transfer Properties

In this study, a cross-flow heat recovery-exchanger system operating with unmixed fluids was manufactured and tested. The thermodynamic analysis of the system was presented via determining the variations of exergy loss with Reynolds number. The analysis also included the effects of convergent and divergent plate-type winglets on heat transfer properties of the designed system. Experimental tests consisted of temperature and pressure drop measurements for the Reynolds numbers (3000 and 12,000) according to the working conditions of the boiler, fan, preheater, and reheater. The effects of inlet conditions of the working fluids on the heat transfer characteristics were correlated via entropy generation number and exergy loss. The variation of the effectiveness with the number of transfer unit of heat recovery unit was calculated and discussed in terms of literature.

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