Semi-closed greenhouses have been developed in which window ventilation is minimized due to active cooling, enabling enhanced CO2 concentrations at high irradiance. Cooled and dehumidified air is blown into the greenhouse from below or above the canopy. Cooling below the canopy may induce vertical temperature gradients along the length of the plants. Our first aim was to analyze the effect of the positioning of the inlet of cooled and dehumidified air on the magnitudes of vertical temperature and VPD gradients in the semi-closed greenhouses. The second aim was to investigate the effects of vertical temperature gradients on assimilate production, partitioning, and fruit growth. Tomato crops were grown year-round in four semiclosed greenhouses with cooled and dehumidified air blown into the greenhouses from below or above the crop. Cooling below the canopy induced vertical temperature and VPD gradients. The temperature at the top of the canopy was over 5°C higher than at the bottom, when outside solar radiation was high (solar radiation >250 J cm-2 h-1). Total dry matter production was not affected by the location of the cooling (4.64 and 4.80 kg m-2 with cooling from above and from below, respectively). Percentage dry matter partitioning to the fruits was 74% in both treatments. Average over the whole growing season the fresh fruit weight of the harvested fruits was not affected by the location of cooling (118 vs 112 g fruit-1). However, during summer period the average fresh fruit weight of the harvested fruits in the greenhouse with cooling from below was higher than in the greenhouse with cooling from above (124 vs 115 g fruit-1).
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At a time when the population is ageing and most people choose to live in their own home for as long as possible, it is important to consider various aspects of supportive and comfortable environments for housing. This study, conducted in South Australia, aims to provide information about the links between the type of housing in which older people live, the weather and occupants’ heating and cooling behaviours as well as their health and well-being. The study used a Computer-Assisted Telephone Interviewing (CATI) system to survey 250 people aged 65 years and over who lived in their own home. The respondents were recruited from three regions representing the three climate zones in South Australia: semi-arid, warm temperate and temperate. The results show that while the majority of respondents reported being in good health, many lived in dwellings with minimal shading and no wall insulation and appeared to rely on the use of heaters and coolers to achieve thermally comfortable conditions. Concerns over the cost of heating and cooling were shared among the majority of respondents and particularly among people with low incomes. Findings from this study highlight the importance of providing information to older people, carers, designers and policy makers about the interrelationships between weather, housing design, heating and cooling behaviours, thermal comfort, energy use and health and well-being, in order to support older people to age in place independently and healthily. https://doi.org/10.1016/j.buildenv.2019.03.023 LinkedIn: https://www.linkedin.com/in/jvhoof1980/
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Turbine blade cooling has been a topic of significant interest, as increasing turbine entry temperatures result in higher cooling requirements. The present numerical method divides the blade into a finite number of elements in the span and peripheral directions and solves the heat transfer fundamental equations for convection and conduction in both directions. As inputs, the span and chord gas temperature and heat transfer coefficient distributions are required. The results include high resolution temperature prediction for the blade and coolant, at all span and chord positions. The advantages of the method include the capturing of blade temperature variation in all directions, while considering the thermal diffusion due to conduction. Mach number effects to the resulted blade and coolant temperature are highlighted, as local distribution of the gas static temperature can have a dominant role. The effect of averaging the input parameters to the predicted blade temperature is discussed and finally, different values for the material conductivity are simulated and the results are analysed.
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