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Irradiation effects on tracking resistance of polymer insulation materials should be investigated due to the increasing usage in radiation-prone environments. This paper presents a study on dc tracking resistance of gamma-ray irradiated polycarbonate mixed with polyethylene by use of IEC 60112 method. The samples were irradiated in air up to 100 kGy and 1000 kGy with a dosage rate of 10 kGy/h using a [sup.60]Co gamma source. Because the data of tracking resistance obtained from the tracking test has a wide variation, discharge current in the test is considered as a main factor to estimate the tracking resistance. A recurrence plot analysis of discharge current has been made to evaluate the tracking resistance more consistently. Obtained results showed that after gamma-ray irradiation, the tracking resistance was improved compared with that of the unirradiated sample. The tracking resistance showed an increasing tendency from 0 kGy to 100 kGy but a decreasing tendency from 100 kGy to 1000 kGy. There was a threshold value for the tracking resistance around 100 kGy, which was related to the reaction of cross-linking and degradation. The topological structures of the recurrence plots with the irradiated samples were different from that of the unirradiated one. There were bigger white space segments, which indicated that there were high amplitude transients in the discharge currents of unirradiated sample. The recurrence point density increased from 100 kGy to 1000 kGy, which suggested that the discharge process of the total dose at 1000 kGy was more intensive than that at 100 kGy. The irradiation effects on the tracking resistance can be visually identified by the recurrence plot. Index Terms--Polycarbonate, polyethylene, gamma-ray irradiation, discharge current, recurrence plot, tracking resistance, degradation, cross-linking.

The thermal modeling and analysis of a transparent insulation materials (TIM) covered solar integrated collector storage (ICS) water heating system with phase-change material (PCM) is carried out in this paper. The system consists of a double rectangular enclosure of cross section 1 m x 1 m where the top enclosure is filled with paraffin wax and that of the bottom is with water. The transient response of the PCM-water solar ICS system is studied with and without fins on the diurnal basis. The performance of the system is investigated with 4, 9, and 19 fins inside the wax having a pitch of 20 cm, 10 cm, and 5 cm, respectively. The latent heat storage with nine fins is found to be optimum for maximum water temperature and minimum heat losses to the surroundings. The temperature of water in the ICS exceeds 50[degrees]C with a temperature drop of only 1.5-2 [degrees]C during nighttime. The nine-fin solar ICS configuration attains ~9[degrees]C higher than other configurations. [DOI: 10.1115/1.2770753] Keywords: integrated-collector-storage system, phase change materials, transparent insulation materials, numerical modeling, fins

ABSTRACT: An overview on the fire performance of fiber-reinforced polymer (FRP) materials and FRP-strengthened reinforced concrete (RC) members is presented. Results from an experimental and numerical research program investigating the [...]

Since the introduction of electrical heat tracing, a major operations Concern has been design considerations for adequately determining the heat loss of valves in piping systems. Analyses have been done on straight pipes and this part of the design is usually well understood and few problems arise with careful design and installation. Valves, supports, instrumentation, and other devices with 'extended surfaces' (noted as 'thermal features' in this paper), if not characterized properly, may cause problems with plant operations. The surface area of a pipe increases linearly with increase in diameter, but the surface area of a valve increases with the square of the pipe diameter for valves. This causes significantly increased heat loss and a lower maintain temperature. A frozen valve on the North Slope of Alaska instigated this paper, but the issues associated with this situation have wider application. A common valve heat loss factor, independent of pipe diameter, is sometimes recommended. Studies have found this causes small-diameter valves to be overheated and large-diameter pipes to be underheated. This paper investigates real heat loss of valve systems on the North Slope of Alaska. Two years of data (800 MB) were analyzed and interpreted, and dynamic experiments were conducted along with building a finite-element model. Thermal insulation of valves is shown to be an area of critical concern. Valves and other 'thermal features' are usually thermally insulated with fabricated blankets with lacing or Velcro used to attach the insulation. This attachment method is used in order to allow access for maintenance. These blankets usually have a lesser thermal insulating capability (larger k factor) than the insulation for the straight pipe. The insulation thickness may also be less. The purpose of this paper is to highlight these parameters and make design recommendations for critical thermal features and large [DELTA]T heat tracing applications. Index Terms--Electrical heat tracing, IEEE 515, IEEE 844, thermal insulation, valve heat loss.

Bioremediation of petroleum-contaminated soils in cold regions is hampered by low temperatures, frozen soils, and short summers. Extreme environmental conditions limit remedial efforts to a few technologies. Bioventing and combined air-sparging and soil vapor extraction have shown promise in subarctic regions. Expensive thermal desorption or encapsulation of organically contaminated soil is practiced in arctic Alaska and Canada, in lieu of successful bioremediation. Thermal insulation systems have recently been developed for innovative bioremediation efforts in cold regions. Commercially available insulation, electrical heating elements, and construction materials have been uniquely packaged to enhance bioremediation at two petroleum-contaminated sites in Alaska. Thermally enhanced bioventing successfully remediated hydrocarbon contamination in the vadose zone at a subarctic site within two years. Preliminary results from an oxygenated and fertilized biopile, actively warmed and covered with a thermal insulation system, shows promise at an arctic site. A guide for thermal insulation system design for bioremediation application in cold regions is developed.

The key components in the selection of a polymer-based material for superconducting applications, case histories of how products have been tailored to meet specific customer demands and descriptions of the generic product types available are described. Several case studies were conducted to illustrate the test methods, product performance features, product tailoring and processing parameters.

A compensating system associated with active thermal insulation improved the performance of OCXO's oven. This compensated oven exhibited the same performance as that of a more bulky thermal enclosure. The compensating principle may also be used in digital systems as the electronics involved are simple in the case of static compensation. The compensating system eliminates dynamic thermal as well as parasitic effects.

A model of household indoor temperature choice is developed and empirically implemented taking into account that indoor temperature exhibits satiety, that temperature is an output of home production, and that there is a natural endowment of outdoor temperature. The model is applied to home heating choices and the welfare effects of an insulation retrofit requirement. (Reprinted by permission of the publisher.)

Did you know that Norwegians are more likely to have invested in solar panels and wind turbines than other OECD countries? Or that the Dutch are the most likely to [...]

A study is presented in which a model is constructed for an empirical comparison of the effects of alternative instruments of environmental policy on the spread of new technology. Specific attention is given to the diffusion of thermal installation in the construction of new housing.