301 resultados para HEAT EXCHANGER EFFICIENCY


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Bovine intestine was dried in a heat pump fluid bed combination. Minimum fluidisation velocity was calculated by Ergun Equation and some relations were established.

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Summary of Actions Towards Sustainable Outcomes Environmental Issues / Principal Impacts The increased growth of cities is intensifying its impact on people and the environment through: • increased use of energy for the heating and cooling of more buildings, leading to urban heat islands and more greenhouse gas emissions • increased amount of hard surfaces contributing to higher temperatures in cities and more stormwater runoff • degraded air quality and noise impact • reduced urban biodiversity • compromised health and general well-being of people Basic Strategies In many design situations boundaries and constraints limit the application of cutting EDGe actions. In these circumstances designers should at least consider the following: • Consider green roofs early in the design process in consultation with all stakeholders to enable maximised integration with building systems and to mitigate building cost (avoid constructing as a retrofit). • Design of the green roof as part of a building’s structural, mechanical and hydraulic systems could lead to structural efficiency, the ability to optimise cooling benefits and better integrated water recycling systems. • Inform the selection of the type of green roof by considering its function, for example designing for social activity, required maintenance/access regime, recycling of water or habitat regeneration or a combination of uses. • Evaluate existing surroundings to determine possible links to the natural environment and choice of vegetation for the green roof with availability of local plant supply and expertise. Cutting EDGe Strategies • Create green roofs to contribute positively to the environment through reduced urban heat island effect and building temperatures, to improved stormwater quality, increased natural habitats, provision of social spaces and opportunity for increased local food supply. • Maximise solar panel efficiency by incorporating with design of green roof. • Integrate multiple functions for a single green roof such as grey water recycling, food production, more bio-diverse plantings, air quality improvement and provision of delightful spaces for social interaction. Synergies & references • BEDP Environment Design Guide DES 53: Roof and Facade Gardens GEN 4: Positive Development – designing for Net Positive Impacts TEC 26: Living Walls - a way to green the built environment • Green Roofs Australia: www.greenroofs.wordpress.com • International Green Roof Association: www.igra-world.com • Green Roofs for Healthy Cities (USA): www.greenroofs.org • Centre for Urban Greenery and Ecology (Singapore): http://research.cuge.com.sg

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Background: There is no global definition of a heatwave because local acclimatisation and adaptation influence the impact of extreme heat. Even at a local level there can be multiple heatwave definitions, based on varying temperature levels or time periods. We investigated the relationship between heatwaves and health outcomes using ten different heatwave definitions in Brisbane, Australia. ---------- Methodology/Principal Findings: We used daily data on climate, air pollution, and emergency hospital admissions in Brisbane between January 1996 and December 2005; and mortality between January 1996 and November 2004. Case-crossover analyses were used to assess the relationship between each of the ten heatwave definitions and health outcomes. During heatwaves there was a statistically significant increase in emergency hospital admissions for all ten definitions, with odds ratios ranging from 1.03 to 1.18. A statistically significant increase in the odds ratios of mortality was also found for eight definitions. The size of the heat-related impact varied between definitions.---------- Conclusions/Significance Even a small change in the heatwave definition had an appreciable effect on the estimated health impact. It is important to identify an appropriate definition of heatwave locally and to understand its health effects in order to develop appropriate public health intervention strategies to prevent and mitigate the impact of heatwaves.

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Several key issues need to be resolved before an efficient and reproducible Agrobacterium-mediated sugarcane transformation method can be developed for a wider range of sugarcane cultivars. These include loss of morphogenetic potential in sugarcane cells after Agrobacterium-mediated transformation, effect of exposure to abiotic stresses during in vitro selection, and most importantly the hypersensitive cell death response of sugarcane (and other nonhost plants) to Agrobacterium tumefaciens. Eight sugarcane cultivars (Q117, Q151, Q177, Q200, Q208, KQ228, QS94-2329, and QS94-2174) were evaluated for loss of morphogenetic potential in response to the age of the culture, exposure to Agrobacterium strains, and exposure to abiotic stresses during selection. Corresponding changes in the polyamine profiles of these cultures were also assessed. Strategies were then designed to minimize the negative effects of these factors on the cell survival and callus proliferation following Agrobacterium-mediated transformation. Some of these strategies, including the use of cell death protector genes and regulation of intracellular polyamine levels, will be discussed.

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Promoted ignition testing (NASA) Test 17) [1] is used to determine the relative flammability of metal rods in oxygen-enriched atmospheres. A promotor is used to ignite a metal sample rod, initiating sample burning. If a predetermined length of the sample burns, beyond the promotor, the material is considered flammable at the condition tested. Historically, this burn length has been somewhat arbitrary. Experiments were performed to better understand this test by obtaining insight into the effect a burning promotor has on the preheating of a test sample. Test samples of several metallic materials were prepared and coupled to fast-responding thermocouples along their length. Thermocouple measurements and test video were synchronized to determine temperature increase with respect to time and length along each test sample. A recommended flammability burn length, based on a sample preheat of 500 degrees fahrenheit, was determined based on the preheated zone measured from these tests. This length was determined to be 30 mm (1.18 in.). Validation of this length and its rationale are presented.

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Pipe insulation between the collector and storage tank on pumped storage (commonly called split), solar water heaters can be subject to high temperatures, with a maximum equal to the collector stagnation temperature. The frequency of occurrence of these temperatures is dependent on many factors including climate, hot water demand, system size and efficiency. This paper outlines the findings of a computer modelling study to quantify the frequency of occurrence of pipe temperatures of 80 degrees Celsius or greater at the outlet of the collectors for these systems. This study will help insulation suppliers determine the suitability of their materials for this application. The TRNSYS program was used to model the performance of a common size of domestic split solar system, using both flat plate and evacuated tube, selective surface collectors. Each system was modelled at a representative city in each of the 6 climate zones for Australia and New Zealand, according to AS/NZS4234 - Heat Water Systems - Calculation of energy consumption, and the ORER RECs calculation method. TRNSYS was used to predict the frequency of occurrence of the temperatures that the pipe insulation would be exposed to over an average year, for hot water consumption patterns specified in AS/NZS4234, and for worst case conditions in each of the climate zones. The results show; * For selectively surfaced, flat plate collectors in the hottest location (Alice Sprints) with a medium size hot water demand according to AS/NZS2434, the annual frequency of occurrence of temperatures at and above 80 degrees Celsius was 33 hours. The frequency of temperatures at and above 140 degrees Celsius was insignificant. * For evacuated tube collectors in the hottest location (Alice Springs), the annual frequency of temperatures at and above 80 degrees Celsius was 50 hours. Temperatures at and above 140 degrees Celsius were significant and were estimated to occur for more than 21 hours per year in this climate zone. Even in Melbourne, temperatures at and above 80 degrees can occur for 12 hours per year and at and above 140 degrees for 5 hours per year. * The worst case identified was for evacuated tube collectors in Alice Springs, with mostly afternoon loads in January. Under these conditions, the frequency of temperatures at and above 80 degrees Celsius was 10 hours for this month only. Temperatures at and above 140 degrees Celsius were predicted to occur for 5 hours in January.