Compressors and condensing units for refrigeration. Performance testing and test methods

The past two decades have seen significant efforts to standardize a series of simplified test methods to characterize the dynamic modulus (DM) and repeated load permanent deformation (RLPD) performance characteristics of asphalt mixtures using the asphalt mixtures performance tester (AMPT). While the current AASHTO T 79 test specifications for the AMPT are faster and easier to perform than their preceding research grade test protocols, there is still reluctance among highway agencies and industry to conduct performance testing using the AMPT. One significant reason is the lengthy process of sample preparation and testing for the DM and RLPD tests. Two studies to expedite this process are reported here. First, the potential for abbreviating the DM testing procedure was examined. It provides the option to fully exclude testing at 40°C by adding an additional frequency of 0.01 Hz at 20°C. This approach reduces time for testing as well as for sample conditioning at high temperature. Second, the possibility of reducing the total number of required specimens was evaluated. The variation of the DM under repetitive testing and the appropriateness of performing the RLPD test on samples already tested for DM were evaluated. The results showed that specimen damage or densification because of DM testing is insignificant. As a consequence, DM test specimens can be re-used for RLPD testing, reducing the required number of samples from 12 to 9.

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Performance of Hot and Cold Recycled Mixtures with High Reclaimed Asphalt Pavement Content

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198120931510 ◽

2020 ◽

Vol 2674 (9) ◽

pp. 714-726

Author(s):

Edith Arámbula-Mercado ◽

Santiago J. Chavarro-Muñoz ◽

Sheng Hu ◽

Howie Moseley

Keyword(s):

Urban Areas ◽

Life Cycle Cost ◽

Asphalt Pavement ◽

Performance Testing ◽

Hydrated Lime ◽

Test Methods ◽

Reclaimed Asphalt Pavement ◽

Moisture Susceptibility ◽

Reclaimed Asphalt ◽

Maintenance And Rehabilitation

Florida Department of Transportation yearly maintenance and rehabilitation activities include milling and resurfacing of approximately 2,000 lane miles of roadway, with an average resurfacing depth of about 2.1 in. (55 mm). These activities result in the generation and accumulation of roughly 1.8 million tons of reclaimed asphalt pavement (RAP) each year. The use of elevated quantities of RAP in asphalt pavement provides an environmentally responsible solution to the accumulated RAP surplus in some urban areas, while at the same time offering an economical pavement maintenance and rehabilitation option to local agencies facing budget constraints. The objective of this project was to compare the performance of mixtures with 60% RAP content to be used primarily on low volume roads (average daily traffic <750 vehicles) and suggest adequate test methods within the context of a balanced mix design approach. To accomplish this objective, three types of mixtures were considered: hot, cold with emulsion, and cold with foamed binder. Performance testing included intermediate temperature cracking, rutting, moisture susceptibility, and durability. The hot recycled mixtures showed good moisture susceptibility and cracking resistance, especially when rejuvenators were incorporated. The cold recycled mixtures showed poor moisture susceptibility and durability characteristics, which were alleviated when hydrated lime or Portland cement was incorporated in the emulsified and foamed mixtures, respectively. Most hot recycled mixtures, and all the cold recycled mixtures, exhibited poor rutting behavior, likely because of the harsh conditions of the test. A life-cycle cost analysis demonstrated more favorable savings when cold recycled mixtures were used.

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Research on Chinese Codes and Standards of Heat Transfer Performance Testing for Heat Exchangers

Volume 1: Codes and Standards ◽

10.1115/pvp2020-21352 ◽

2020 ◽

Author(s):

Bin Ren ◽

Xiaoying Tang ◽

Facai Ren ◽

Jibing Wang ◽

Bofeng Bai

Keyword(s):

Heat Transfer ◽

Heat Exchangers ◽

Performance Test ◽

Heat Transfer Performance ◽

Performance Testing ◽

Test Methods ◽

Transfer Performance ◽

Factors Affecting ◽

Nonlinear Fitting ◽

Test Standards

Abstract Heat exchanger is a device that transfers heat between hot and cold fluids. Due to the different size and type, the actual heat transfer performance is usually not the same as the design value. Meanwhile, various heat exchangers using new types of heat transfer elements have emerged, bringing the difficulty to obtain the heat transfer performance by only theoretical calculation. Therefore, studying test methods and developing test standards for heat exchangers have become the research focus in many countries. In this paper, the basic principles of various performance test methods are firstly introduced, including Wilson plot method, equal Reynolds number method and nonlinear fitting method. Then the restrictions on the use of these methods and the factors affecting the test results are analyzed. Finally, the Chinese codes and standards of performance testing for heat exchangers are listed, including JB/T 10379-2002, GB/T 27698-2011 and TSG R0010-2019. The test methods used in GB/T 27698 are described in detail. The results show that GB 27698 mainly focus on the specification of testing systems and procedures and can test heat transfer performance of almost all types of heat exchangers in industry under different heat transfer modes. However, there are lack of formulas and methods for calculating uncertainty of testing results.

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Three decades of international RILEM activities to combat deleterious Alkali-Silica Reactions (ASR) in concrete.

MATEC Web of Conferences ◽

10.1051/matecconf/201819903001 ◽

2018 ◽

Vol 199 ◽

pp. 03001

Author(s):

Børge Johannes Wigum ◽

Jan Lindgård

Keyword(s):

State Of The Art ◽

Construction Materials ◽

Performance Testing ◽

Test Methods ◽

Alkali Content ◽

International Union ◽

Field Exposure ◽

Performance Based Assessment

Since 1988, the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM) Technical Committees (TCs) have been seeking to establish universally applicable test methods for assessing the alkali-reactivity potential of aggregates, and from later on, for concrete mixes. TC 106 (1988 – 2001) focused on accelerated aggregate tests. The successor committee TC 191-ARP (2001 – 2006) also included work on diagnosis/appraisal & specification. TC 219-ACS (2006 – 2014) introduced work on performance testing & modelling. The major recommendations were published as a RILEM State-of-the-art Report in 2016. In 2014, TC 258-AAA was established, scheduling to finish the work on performance-based assessment in 2019. This current TC is focusing on the following Work Packages; WP1Performance based testing concepts, WP2 Relationship between results from laboratory and field and the establishment of field exposure sites, WP3 Testing of potential alkalis released from certain types of aggregates and measurement of internal concrete alkali content, and eventually; WP4 Verification of alkalis released from aggregates.

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Environmental Performance Testing System for Thermostructure Materials Applied in Aeroengines

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.313.183 ◽

2006 ◽

Vol 313 ◽

pp. 183-0 ◽

Cited By ~ 19

Author(s):

Li Tong Zhang ◽

Lai Fei Cheng ◽

Xin Gang Luan ◽

Hui Mei ◽

Yong Dong Xu

Keyword(s):

Environmental Performance ◽

Thermal Stresses ◽

Performance Test ◽

Performance Testing ◽

Ceramic Matrix Composites ◽

Test Methods ◽

Testing System ◽

Matrix Composites ◽

Innovative Methodology ◽

Service Environments

The conventional ultimate performance test by applying a component in its true application (i.e., in an engine) is often very expensive and impractical when dealing with developmental materials. Simpler, less expensive, and more practical test methods must be utilized. The present work aims toward the applications of an innovative methodology for testing environmental performance of advanced Ceramic Matrix Composites (CMCs) in the presence of combined mechanical, thermal, and environmental applied conditions. To obtain a comprehensive understanding of how a composite might perform in certain application environments, a newly developed environmental performance testing system, which is able to provide the fundamental damage information of the composites in simulating service environments including variables such as temperature, mechanical and thermal stresses, flowing oxidizing gases and high gas pressure, is proposed. The system comprises of two subsystems: (1) equivalent experimental simulating subsystem, and (2) wind tunnel experimental simulating subsystem. The evolution mechanisms of the composites properties and microstructures can be achieved by the former, and then be validated and modified by the latter. Various loading (e.g. fatigue, creep), various atmospheres (e.g. argon, oxygen, water vapor, wet oxygen and molten salt vapor) and various temperature conditions (e.g. constant or cyclic temperatures) can be conducted on the system. Some typical experimental results are presented in this paper. Large quantities of tests have demonstrated the extraordinary stability and reliability of the system.

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