scholarly journals Effect of aging and interaction of cooling fluid with heat exchangers material in long-lasting durability test

2019 ◽  
Vol 177 (2) ◽  
pp. 187-192
Author(s):  
Joanna FABER ◽  
Zbigniew JURASZ ◽  
Krzysztof BRODZIK
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Ph Value ◽  
Aging Effect ◽  
Durability Test ◽  
Cooling Fluid ◽  
Engine Cooling ◽  
In The Beginning ◽  
Glycol Solution

Efforts to improve engine cooling efficiency by usage of heat exchanger as well as research on cooling fluids composition and properties are well described. Studies on heat exchangers are focused mainly on their durability properties, while cooling fluids development is lately concentrating on nanofluids. In this paper physicochemical properties changes of diluted glycol-based cooling fluid in a long-term durability test of vehicle heat exchanger, were investigated. Following parameters were measured: density of coolant, pH value, elements content in coolant, and reserve alkalinity. Above mentioned analyses were performed on samples collected both in the beginning and periodically after every 500 hours of durability test which lasted for 3000 hours in total. The performed study leads to conclusion that interaction of cooling fluid with material of heat exchanger and changes in glycol composition during long-lasting durability test allows to determine aging effect of applied glycol solution on heat exchanger wear.

Steam Condensation in Parallel Channels of Plate Heat Exchangers

2010 ◽  
Author(s):  
Prabhakara Rao Bobbili ◽  
Bengt Sunden
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Flow Distribution ◽  
Small Degree ◽  
Flow Conditions ◽  
Steam Condensation ◽  
Cooling Fluid ◽  
Plate Heat ◽  
Parallel Channels ◽  
Flow Maldistribution

An experimental investigation has been carried out to find the nature of temperature profiles of the process and cooling fluids during steam condensation across the port to channel in plate heat exchangers (PHEs). In the present study, low corrugation angle (30°) plates have been used for different plate package of PHEs with 41 and 81 plates. The process steam entered at 1 bar with a small degree of superheat. Water has been used as the cold fluid. A traverse temperature probe is inserted into both inlet and outlet ports of the plate heat exchanger. The temperature of the process steam and cooling fluid have been measured and recorded at the location of first, middle and last channels for different inlet and exit flow conditions for each plate package of the heat exchanger. Also, the overall pressure drop has been measured at different conditions at the outlet of the process steam, i.e., full and partial condensation. The traverse temperature measurements have indicated that there is a considerable variation in temperature along inlets and outlets of process steam and cooling fluid, due to flow maldistribution. The experimental data has been analyzed to show how the flow distribution on the cooling side affects the condensation of steam in plate heat exchangers. The present results will help to study further the nature of steam condensation in parallel channels of heat exchangers.

Development of Ceramic Heat Exchangers for Indirect Fired Gas Turbines

1982 ◽  
Author(s):  
W. T. Bakker ◽  
D. Kotchick
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Gas Turbines ◽  
Large Scale ◽  
Working Fluid ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Short Term ◽  
The Status

Utilizing dirty fuels such as coal in gas turbine engines requires that heat input to the cycle working fluid occur through a heat exchanger. For high cycle efficiencies such a heat exchanger must operate in the 700–1400 KPA, 1100–1200°C (100–200 psi, 2000–2200°F) range. In this temperature range, ceramic heat exchangers are required. Ceramic heat exchangers that can operate in this regime have been under development for several years on a very modest scale. These programs are briefly reviewed. Major material issues are reviewed and the status of each is presented. Mechanical reliability and joining technology have been successfully demonstrated in short term tests. Long-term durability and the manufacturing technology to produce large scale components reproducibly remains to be demonstrated in the future.

scholarly journals KAJI EKSPERIMENTAL PENGARUH BAFFLE PADA ALAT PENUKAR PANAS ALIRAN SEARAH DALAM UPAYA OPTIMASI SISTEM PENGERING

2019 ◽  
Vol 13 (1) ◽  
pp. 8
Author(s):  
Azwinur Azwinur ◽  
Zulkifli Zulkifli
Keyword(s):  
Fluid Flow ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Fluid Phase ◽  
Field Testing ◽  
Heat Losses ◽  
Cooling Fluid ◽  
Directional Flow ◽  
Drying System ◽  
Guide Blade

Heat exchangers or heat exchangers are tools used to change the temperature of the fluid or change the fluid phase by exchanging heat with another fluid. In a heat exchanger, the ability to exchange heat is largely determined by the type of fluid flow and fluid passing through the heat exchanger. The use of heat exchangers in the field of drying is now a necessity to overcome the problems of drying productivity. The purpose of this study was carried out to determine the effectiveness of the heat exchanger experimentally based on directional flow by comparing construction using baffle and without using baffle in an effort to optimize the drying system. The research method was carried out by fabricating 2 units of heat exchangers and by field testing. The test data obtained are the input and output temperatures of the heating fluid flow and cooling fluid flow and flow velocity. Based on preliminary research data shows that the use of baffle affects the increase in temperature on the heat exchanger, where at the fresh air outlet that does not use baffle produces a temperature of 72oC while the baffle produces 88oC with the Log Mean Temperature Difference heat exchanger without using a baffle higher than heat exchanger that uses a baffle guide blade. This can illustrate that the smaller heat losses are wasted so that the absorption of heat by the reverse system will be higher.

On-site monitoring in a passive house

2011 ◽  
Vol 2 (1) ◽  
pp. 39-44
Author(s):  
T. Csoknyai ◽  
A. Talamon
Keyword(s):  
Heat Exchangers ◽  
First Year ◽  
Passive House ◽  
Site Monitoring ◽  
First Results ◽  
Long Term Monitoring ◽  
In The Beginning ◽  
Building Occupancy ◽  
Term Monitoring

Abstract In the beginning of August 2009 a long-term monitoring started in a recently built passive house near Isaszeg. The first results were presented in the last year's conference. The present paper gives an overview about a whole-year data evaluation focusing on energy consumption. During the first year of building occupancy three types of heat suppliers and two types of heat exchangers in the ventilation systems were applied and monitored, thus different heating options could be compared.

Geotechnical Considerations in the Design of Borehole Heat Exchangers

2020 ◽  
Author(s):  
Despina Maria Zymnis ◽  
Andrew J. Whittle
Keyword(s):  
Heat Exchanger ◽  
Parametric Study ◽  
Heat Exchangers ◽  
Design Parameters ◽  
Ground Source Heat Pumps ◽  
Heat Exchanger Design ◽  
Heating And Cooling ◽  
Adjacent Structures ◽  
Borehole Heat Exchangers

The use of ground source heat pumps to transfer heat to and from the ground via borehole heat exchangers (BHE) is among the most energy efficient techniques for space heating and cooling. Broader applications in urban environments require more careful evaluation of hydro-mechanical behavior of soil to ensure their reliable long-term performance and to minimize adverse effects on adjacent structures. An advanced soil model has been integrated within a finite difference (FD) framework, to solve coupled thermo-hydro-mechanical (THM) problems in an axisymmetric space. The FD simulator is applied to a prototype project and the ground conditions represent typical stress history profiles found in Geneva, Switzerland. An extensive parametric study is undertaken to study the long-term THM response of clay for a broad range of heat exchanger design parameters. The results show that significant settlements can be induced due to the long-term operation of BHEs (i.e., over periods from 10–50 years). The parametric study gives useful guidelines for heat exchanger design and identifies a design space of optimum solutions that meet pre-specified foundation settlement criteria. The study provides a qualitative investigation and a systematic framework for analyzing the long-term THM response of clay to seasonal heating and cooling.

Energy Efficient Polymers for Gas-Liquid Heat Exchangers

2008 ◽  
Author(s):  
Patrick Luckow ◽  
Avram Bar-Cohen ◽  
Peter Rodgers ◽  
Juan Cevallos
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Conductive Polymer ◽  
Coefficient Of Performance ◽  
Offshore Platforms ◽  
Compression Process ◽  
Cooling Fluid ◽  
Thermally Conductive ◽  
Liquid Heat ◽  
Better Than

The present study explores the thermofluid characteristics of a seawater-methane heat exchanger that could be used in the liquefaction of natural gas on offshore platforms. The compression process generates large amounts of heat, usually dissipated via plate heat exchangers using seawater as a convenient cooling fluid. Such an application mandates the use of a corrosion resistant material. Metals such as titanium, expensive in terms of both energy and currency, are a common choice. The “total coefficient of performance,” or COPT, which incorporates the energy required to manufacture a heat exchanger along with the pumping power expended over the lifetime of the heat exchanger, is used to compare conventional metallic materials to thermally conductive polymers. The results reveal that heat exchangers fabricated of low energy, low thermal conductivity polymers can perform as well as, or better than, those fabricated of conventional materials, over the full lifecycle of the heat exchanger. Analysis of a prototypical seawater-methane heat exchanger, built from a thermally conductive polymer, suggests that a COPT nearly double that of aluminum, and more than ten times that of titanium, could be achieved.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

scholarly journals Review of the Durability of Polymer Electrolyte Membrane Fuel Cell in Long-Term Operation: Main Influencing Parameters and Testing Protocols

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4048
Author(s):  
Huu Linh Nguyen ◽  
Jeasu Han ◽  
Xuan Linh Nguyen ◽  
Sangseok Yu ◽  
Young-Mo Goo ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Failure Modes ◽  
Polymer Electrolyte Membrane ◽  
Durability Test ◽  
Term Operation ◽  
Electrolyte Membrane ◽  
Transportation Applications ◽  
Testing Protocols

Durability is the most pressing issue preventing the efficient commercialization of polymer electrolyte membrane fuel cell (PEMFC) stationary and transportation applications. A big barrier to overcoming the durability limitations is gaining a better understanding of failure modes for user profiles. In addition, durability test protocols for determining the lifetime of PEMFCs are important factors in the development of the technology. These methods are designed to gather enough data about the cell/stack to understand its efficiency and durability without causing it to fail. They also provide some indication of the cell/stack’s age in terms of changes in performance over time. Based on a study of the literature, the fundamental factors influencing PEMFC long-term durability and the durability test protocols for both PEMFC stationary and transportation applications were discussed and outlined in depth in this review. This brief analysis should provide engineers and researchers with a fast overview as well as a useful toolbox for investigating PEMFC durability issues.

scholarly journals Effects of Sugar Cane Molasses Addition on the Fermentation Quality, Microbial Community, and Tastes of Alfalfa Silage

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 355
Author(s):  
Runbo Luo ◽  
Yangdong Zhang ◽  
Fengen Wang ◽  
Kaizhen Liu ◽  
Guoxin Huang ◽  
...  
Keyword(s):  
Sugar Cane ◽  
Ph Value ◽  
Electronic Tongue ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Cane Molasses ◽  
Fermentation Quality ◽  
Alfalfa Silage ◽  
Additive Control

The objective was to study the effects of sugar cane molasses addition on the fermentation quality and tastes of alfalfa silage. Fresh alfalfa was ensiled with no additive (Control), 1% molasses (M1), 2% molasses (M2), and 3% molasses (M3) for 206 days. The chemical composition and fermentation characteristics of the alfalfa silages were determined, the microbial communities were described by 16S rRNA sequencing, and the tastes were evaluated using an electronic tongue sensing system. With the amount of added molasses (M), most nutrition (dry matter and crude protein) was preserved and water-soluble carbohydrates (WSC) were sufficiently used to promote the fermentation, resulting in a pH reduction from 5.16 to 4.48. The lactic acid (LA) content and LA/acetic acid (AA) significantly increased, indicating that the fermentation had turned to homofermentation. After ensiling, Enterococcus and Lactobacillus were the dominant genus in all treatments and the undesirable microbes were inhibited, resulting in lower propionic acid (PA), butyric acid (BA), and NH3-N production. In addition, bitterness, astringency, and sourness reflected tastes of alfalfa silage, while umami and sourness changed with the amount of added molasses. Therefore, molasses additive had improved the fermentation quality and tastes of alfalfa silage, and the M3 group obtained the ideal pH value (below 4.5) and the best condition for long-term preservation.

scholarly journals LifePlanning: A Better Retirement Planning Option for Our Times

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 111-112
Author(s):  
Rajiv Nagaich ◽  
Carol Redfield ◽  
Ben Harvill
Keyword(s):  
Institutional Care ◽  
Integrated Approach ◽  
Retirement Planning ◽  
Practice Research ◽  
Care Needs ◽  
Term Care ◽  
Investment Returns ◽  
The Many ◽  
In The Beginning

Abstract Ten thousand turn 65 daily. Majority look forward to retiring in the beginning and then become afraid of outcomes they often hear about- dealing with institutional care, becoming a burden, or running out of money. This is not because retirees do not plan, but despite of having planned their entire life for retirement. Many employers provide financial retirement planning such as a 401K plan. Individuals have relied on employee benefit plans to ready themselves, yet few are “very confident” about it. Two-thirds of retirees say their most recent employers did “nothing” to help them transition into retirement; 16% are “not sure” what their employers did. Many may be overlooking important factors in their strategies. Among retirees who currently have a retirement strategy, 85% have factored Social Security and Medicare benefits into their strategy. Most have included on-going living expenses (79%), total savings and income needs (57%) into their plan. Fewer than half have considered other critical factors (e.g., investment returns, ongoing healthcare costs, inflation, long-term care needs, tax planning, etc.). Only 9% have contingency plans for retiring sooner than expected and/or savings shortfalls. The truth is that education offered by employers tends to be traditional planning advice, which may not be enough to address the concerns retirees will have in retirement. To this, we introduce a multi-disciplinary LifePlanning Framework which takes a wholistic, integrated approach in addressing the many complex issues of retirement found in health, housing, finance, legal, and family. Our results may impact future practice, research, and policy.

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