scholarly journals Applying Petroleum Pressure Buildup Well Test Procedure on Thermal Response Test—A Novel Method to Improve Accuracy of Thermal Conductivity Determination

2017 ◽  
Author(s):  
Tomislav Kurevija ◽  
Kristina Strpić ◽  
Sonja Koščak-Kolin
Keyword(s):  
Thermal Conductivity ◽  
Test Procedure ◽  
Thermal Response ◽  
Conductivity Measurement ◽  
Test Method ◽  
Test Time ◽  
Testing Time ◽  
Well Test ◽  
Improve Accuracy ◽  
Ground Conductivity

Theory of the Thermal Response Testing (TRT) is a well-known part of sizing process of the geothermal exchange system. Multiple parameters influence accuracy of effective ground thermal conductivity measurement; like testing time, variable power, climate interferences, groundwater effect etc. To improve accuracy of the TRT we introduced procedure to additionally analyze falloff temperature decline after power test. Method is based on a premise of analogy between TRT and petroleum well testing, since origin of both procedures lies in diffusivity equation with solutions for heat conduction or pressure analysis during radial flow. Applying pressure build-up test interpretation technique to the borehole heat exchanger testing, greater accuracy could be achieved since ground conductivity could be obtained from this period. Analysis was conducted on coaxial exchanger with five different power steps, and with both direct and reverse flow regime. Each test was set with 96hr of a classical TRT, followed by 96hr of temperature decline, making it almost 2000 hours of cumulative borehole testing. Results showed that ground conductivity value could vary as much as 25% depending on test time, seasonal period and power fluctuations while thermal conductivity obtained from a falloff period gives more stable values with only 10% value variation.

A Development of a New Life Test Procedure for Fan Motors

2006 ◽  
Vol 321-323 ◽  
pp. 1539-1542
Author(s):  
Wae Gyeong Shin ◽  
Soo Hong Lee ◽  
Young Sik Song
Keyword(s):  
Automotive Industry ◽  
Field Condition ◽  
Test Procedure ◽  
Test Method ◽  
Accelerated Life Test ◽  
Test Time ◽  
Life Test ◽  
Dc Motors ◽  
Accelerated Life ◽  
Automotive Parts

Reliability of automotive parts has been one of the most interesting fields in the automotive industry. Especially small DC motor was issued because of the increasing adoption for passengers’ safety and convenience. For several years, small DC motors have been studied and some problems of a life test method were found out. The field condition was not considered enough in the old life test method. It also needed a lot of test time. For precise life estimation and accelerated life test, new life test procedure was developed based on measured field condition. First, vibration condition on vehicle and latent force on fan motor shaft were measured and correlated with each other. Second, test condition was decided by obtained data. Finally, life of fan motors was estimated by new life test method in shorter test time.

scholarly journals Transparent Vacuum Insulation Panels

2021 ◽  
Author(s):  
Takao Katsura
Keyword(s):  
Thermal Conductivity ◽  
Low Cost ◽  
Conductivity Measurement ◽  
Test Method ◽  
Total Thickness ◽  
Gas Barrier ◽  
Vacuum Insulation ◽  
Apparent Thermal Conductivity ◽  
Heat Flux Meter ◽  
Insulation Performance

New, low-cost transparent vacuum insulation panels (TVIPs) using structured cores for the windows of existing buildings are proposed. The TVIP is produced by inserting the structured core, the low-emissivity film, and the adsorbent into the transparent gas barrier envelopes. In this chapter, the authors introduce the outlines, the design and thermal analysis method, the performance evaluation (test) method. Firstly, five spacers, namely peek, modified peek, mesh, silica aerogel, and frame, are selected as the structured core. The effective thermal conductivity of TVIPs with five different spacers is evaluated at different pressure levels by applying numerical calculation. The result indicated that TVIPs with frame and mesh spacers accomplish better insulation performance, with a center-of-panel apparent thermal conductivity of 7.0 × 10−3 W/m K at a pressure of 1 Pa. The apparent thermal conductivity is the same as the value obtained by the simultaneous evacuation thermal conductivity measurement applying the heat flux meter method. Furthermore, using a frame-type TVIP with a total thickness of 3 mm attached to an existing window as a curtain decreases the space heat loss by approximately 69.5%, whereas the light transparency decreases to 75%.

Thermal Conductivity Measurement of Aluminum Oxide Nanofluids Using the 3-Omega Method

2006 ◽  
Author(s):  
Dong-Wook Oh ◽  
Ankur Jain ◽  
John K. Eaton ◽  
Kenneth E. Goodson ◽  
Joon Sik Lee
Keyword(s):  
Thermal Conductivity ◽  
Thermal Response ◽  
Conductivity Measurement ◽  
Solid Particles ◽  
Omega 3 ◽  
Omega Method ◽  
Wire Method ◽  
3 Omega ◽  
Good Agreement ◽  
3 Omega Method

Nanofluids, which are suspensions of nano-sized solid particles in a liquid medium, show remarkable enhancement in thermal conductivity compared to the base fluid. Nanofluids are a promising candidate for advanced heat transfer applications such as microelectronics cooling. While the thermal conductivity of nanofluids has been measured in the past using conventional techniques such as the transient hot wire method, this work presents the application of the 3-omega (3-ω) method for this purpose. The theoretical model for 3-ω response of a heater device with de-ionized (DI) water is verified by comparing with experimental measurements. Following this validation, the effective thermal conductivity of Al2O3 nanofluids in DI water and ethylene glycol are measured. The measured values are found to be in good agreement with previous works. In addition, interesting effects in the thermal response due to agglomeration and sedimentation of nanoparticles are observed.

Thermal conductivity measurement of rock fragments using a pulsed needle probe

1993 ◽  
Vol 30 (3) ◽  
pp. 480-485 ◽  
Author(s):  
T. J. Lewis ◽  
H. Villinger ◽  
E. E. Davis
Keyword(s):  
Thermal Conductivity ◽  
Asymptotic Relation ◽  
Pulse Length ◽  
Thermal Response ◽  
Conductivity Measurement ◽  
Heat Pulse ◽  
Origin Time ◽  
Temperature Conductivity ◽  
Rock Fragments ◽  
Needle Probe

A heat pulse generated inside a needle probe can be used to measure the thermal conductivity of surrounding rock fragments or drill cuttings. As the pulse of heat is conducted outwards into the surrounding aggregate of rock fragments and water, the decrease in temperature inside the probe is recorded as a function of time. An asymptotic relation between probe temperature, conductivity, and inverse time since the heat pulse is shown to be accurate for the range of times used. The relatively slow thermal response of the probe in samples with higher conductivities is accommodated by a delay in the origin time of the pulse. The combined correction for finite pulse length and slow probe response is shown to be small and predictable. The thermal conductivity of rock fragments is calculated from a model that is dependent on the water content of the sample, as in other methods. Results using this method and a divided bar apparatus are equivalent, given the expected accuracy of a divided bar. The measured thermal conductivities of water, fused quartz, and crystalline quartz compare closely with their accepted values.

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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