Temperature-Based Criteria for Opening Newly Laid Repaired Asphalt Pavement Sections to Traffic

To avoid premature damage, a newly laid asphalt pavement repair must be allowed to cool sufficiently before opening to air traffic. This study examines the variations of temperature within different repaired asphalt layers during cooling, and makes recommendations with regard to the choice of temperature-based criteria for determining the earliest time to open a newly laid asphalt pavement section to air traffic in a busy airport. Using finite element simulation analysis, the cooling patterns of asphalt layers under the following conditions were studied: three different weather conditions (sunny daytime, cloudy daytime, and nighttime) with three different wind speeds. It is shown that the common practice of relying on surface temperature to determine the time for opening to traffic is unsatisfactory. This is because under most paving conditions, a large proportion of the newly laid asphalt layer would still have temperatures higher than the surface temperature. From finite element analysis for different paving and environmental conditions, it is recommended that the temperatures at an interior point be measured at either 1/2, 2/3, or 3/4 depth, and that nighttime paving be preferred. This study shows that for common asphalt pavement repairs of thicknesses up to 150 mm, taking the temperature at either 2/3 or 3/4 depth as the guide, a repaired asphalt layer, when opened to air traffic, would have its internal maximum temperature kept within 2°C of the preset maximum allowable temperature. If the 1/2 depth temperature is selected as a guide, a margin of within 4°C of the preset maximum allowable temperature can be achieved.

Study of heat resistance of epoxy matrix modified by phthalimide for protection of vehicles

The perspectives of using new modified polymer-based materials for the restoration of vehicle parts are substantiated in this article. The use of binders based on epoxy diane oligomers is proved to be promising in the formation of anti-corrosion coatings. To improve the properties of epoxy matrices at the preliminary stage of their formation, active additives are introduced. The use of a phthalimide modifier, which contains functional groups active before interfacial interaction, is proved to be promising as well. An epoxy diane oligomer is selected as the binder‘s main component in the formation of composites. The hardener polyethylene polyamine is used for crosslinking the epoxy compositions. It allows to harden materials at room temperatures. The choice of a phthalimide modifier for the improvement of thermophysical properties of the developed materials is substanciated. Heat resistance (according to Martens), glass transition temperature and thermal coefficient of linear expansion of modified epoxy composites are studied. To form a composite material or protective coating with improved thermophysical properties, the modifier phthalimide in the amount of q = 0.25… 0.50 pts. wt. at q = 100 pts. wt. of epoxy oligomer ED-20 should be introduced into the epoxy binder. Based on the tests of thermophysical properties of phthalimide-modified materials, the allowable temperature limits, at which it is possible to use the developed composites, are found.

Optimal temperature overshoot profile found by limiting global sea level rise as a lower-cost climate target

The global temperature targets of limiting surface warming to below 2.0°C or even to 1.5°C have been widely accepted through the Paris Agreement. However, limiting surface warming has previously been proven insufficient to control sea level rise (SLR). Here, we explore a sea level target that is closer to coastal planning and associated adaptation measures than a temperature target. We find that a sea level target provides an optimal temperature overshoot profile through a physical constraint of SLR. The allowable temperature overshoot leads to lower mitigation costs and more effective long-term sea level stabilization compared to a temperature target leading to the same SLR by 2200. With the same mitigation cost as the temperature target, a SLR target could bring surface warming back to the targeted temperatures within this century, lead to a reduction of surface warming of the next century, and reduce and slow down SLR in the centuries thereafter.

Studies on Behaviour of in Service Tubular Material Used at Refinery Process Furnaces

The purpose of the heat transfer analysis at the level of the technological furnace in radiation section was to determine the medium temperature on the outside wall of the pipeline through which the effluent is processed. It is important to keep an outside temperature of the wall of the duct below the maximum allowable temperature at which this carburizing process takes place. Thus, the temperature calculated on the outside pipe wall is 523.5 oC and the maximum allowable temperature of the outside pipe wall is 595.5oC. The carburizing process leads to the modification of the thermal conductivity of the tubing material. Therefore, if steel is enriched with carbon, thermal conductivity decreases.

Heat Radiation Effect of Passenger Car Headlamp Using Plate Heat Pipe

The existing heat pipe applied to a LED headlamp has a large size although it has only small area of contact. Therefore, it is difficult to achieve a harmonious radiation of heat along with the difficulty in attaching the LED due to its large volume. This study proposed a plate heat pipe to solve the aforementioned problems. Through the study, the effects of the thickness and acetone filling rate on the heat radiation effects of a plate heat pipe at room temperature and vehicle driving environment were confirmed along with comparison with the heat radiation effects of the existing copper heat pipe. The heat radiation effects were checked by attaching a thermocouple to the evaporator, adiabatic section and condenser of the LED. As the results of the experiment, it was found that a temperature below 120oC, which is the allowable temperature to guarantee the performance of the LED, is maintained. In addition, as the results of comparison of radiation of heat, it was confirmed that the plate heat pipe with a thickness of 2 mm and 20% filled with acetone has a better performance than the existing copper heat pipe.

Mathematical analysis of the effect of the constant temperature assumption in the leak test of PTB Testing Instructions, Volume 25

<p class="Abstract">"PTB Testing Instructions, Volume 25: Gas meters – Test rigs with critical nozzles" (PTB 25) includes a detailed description of a test to evaluate the tightness of the rig (leak test). The mathematical modeling of this test assumes that temperature remains constant, and it is established a maximum allowable change of 0.1 K during the test. PTB 25 defines a maximum value of the leak flow rate as criteria for approval of the test.</p><p class="Abstract">In this work, the effect of the assumption of constant temperature over the leak test result was analyzed. Different processes in which the real leak flow rate was zero and there was a change in the temperature of the system equal to the maximum permissible (according to PTB 25) were simulated, and the leak flow rate calculated by PTB 25’s model was determined. The assumption of constant temperature does not simplifies drastically the mathematical model. It is concluded that PTB 25’s maximum allowable temperature change is too high for most practical situations, leading to errors that exceeds the maximum allowable leakage rate. The factors “test time” and “enclosed volume” have a high effect over the magnitude of the error given by PTB 25’s leak flow rate model.</p>

Prediction and comparison of size of the copper and aluminium bus duct system based on ampacity and temperature variations using MATLAB

The main objective of this paper is to propose an algorithm to predict and compare the sizes of the bus bar with materials like copper and aluminum by considering the allowable ampacity and allowable temperature rise with natural and forced convection cooling arrangement. Theoretical analysis is carried out with modified size of the copper bus bar using MATLAB, to analyze the ampacity and temperature variation under the natural and forced convection mode. The algebraic equation developed from thermal model is solved using MATLAB for the determination of the allowable temperature rise and ampacity of rectangular-section bus bars of copper and aluminum and also for different sizes of bus bar. An algorithm has been developed for the analysis. Experimental observations of temperature variation in copper bus bar with standard size under natural and forced cooling mode are validated with the algebraic equation developed from thermal model is solved using MATLAB. It is concluded that bus bar dimensions are compared for the materials copper and aluminum to predict the suitable equivalent dimensions for the same ampacity level and within the allowable temperature rise to reduce the cost of panel.

A Compression Ratio Selection Method of the Non-Road Diesel Engine Without EGR System to Meet Stage V Emission Standards

Fuel efficiency is the key buying factor in the non-road diesel engine market, because the engine mainly operates in the high torque region and consumes relatively large amount of fuel in a short term. A compression ratio of diesel engine is deeply related to a thermal efficiency and it is one of the key design parameter influencing on the fuel efficiency. In this paper, the new approach to select compression ratio is described and the design constrains such as in-cylinder max allowable pressure, max allowable temperature at turbine front end and max allowable temperature at compressor back end were considered. The base engine is 3.4 liter non-road diesel engine without EGR (Exhaust Gas Recirculation) system for Stage V emission standards and is originated from the same engine system with EGR system to meet Tier 4 Final emission standards. Its official compression ratio is 17.0. The purpose of this study is to select an optimal compression ratio for non-road diesel engine system with non-EGR system to meet Stage V emission standards. The methodology to be presented in this study is based on the 1-D engine performance simulations, the 3-D CFD (Computational Fluid Dynamics) combustion simulations, and the engine bench test. In these simulations, a compression ratio and a SOI (Start of Injection) were considered for sweeping parameters. With analyzing the results of parameter studies and engine design constraints, an optimal compression ratio is found to be 18.0. As a result of many engine bench tests, a fuel consumption has been improved by 1.5% with new piston bowl of which compression ratio is 18.0, meeting Stage V emission standards.

The Concept Study on the New Steam Cooling Reactor

Coolant is an important part of the nuclear reactor, which can convert the fission energy into heat. At the same time, it can cool the core, and control the various components of the reactor in the allowable temperature. In this paper, gas-liquid two-phase flow is proposed as the coolant in the nuclear reactor. Based on the Monte Carlo method of particle transport program GMT program and LITAC program, the neutron performance, thermal hydraulic of nuclear reactor were calculated and analyzed. The operation of the new reactor will not be refuel for decades. The gas-liquid two-phase flow coolant can be used as one of the existing alternative coolants.