Browsing by Author "Boulic M"
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- ItemExperimental Performance of a Solar Air Collector with a Perforated Back Plate in New Zealand(MDPI AG, 2020-03-18) Wang Y; Boulic M; Phipps R; Plagmann M; Cunningham CThis study investigates the thermal efficiency of a solar air heater (SAH), when it was mounted on a custom-made support frame, and was operated under different air mass flow rate. This SAH is composed of a transparent polycarbonate cover plate, a felt absorber layer, a perforated aluminium back plate and an aluminium frame. The ambient inlet air of this SAH is heated as it passes through the perforated back plate and over the felt absorber layer. The heated air is blown out through the outlet. Studies of SAHs with a similar design to this SAH were not found in the literature. The experiment was carried out at Massey University, Auckland campus, NZ (36.7◦ S, 174.7◦ E). The global horizontal solar irradiance, the ambient temperature and the wind speed were recorded using an on-site weather station. Temperature and velocity of the air at the outlet were measured using a hot wire anemometer. During the experiment, the air mass flow rate was between 0.022 ± 0.001 kg/s and 0.056 ± 0.005 kg/s. Results showed that when the SAH was operated at the airflow between 0.0054 kg/s and 0.0058 kg/s, the inlet air temperature and the wind speed (between 0 and 6.0 m/s) did not impact the temperature difference between the outlet air and the inlet air. The thermal efficiency of the SAH increased from 34 ± 5% at the airflow between 0.021 kg/s and 0.023 kg/s, to 47 ± 6% at the airflow ranging from 0.032 kg/s to 0.038 kg/s, to 71 ± 4% at the airflow of 0.056 ± 0.005 kg/s. The maximum thermal efficiency of 75% was obtained at the airflow of 0.057 kg/s. The effective efficiency of the SAH was 32 ± 5% at the airflow between 0.021 kg/s and 0.023 kg/s, 42 ± 6% at the airflow ranging from 0.032 kg/s to 0.038 kg/s, and 46 ± 11% at the airflow of 0.056 ± 0.005 kg/s.
- ItemHeater choice, dampness and mould growth in 26 New Zealand homes: A study of propensity for mould growth using encapsulated fungal spores(MDPI AG, 2015) Boulic M; Phipps RA; Cunningham MJ; Cleland DJ; Fjallstrom P; Keiko P; Howden-Champan PThe relationship between the use of unflued gas heaters (UGH, N = 14) and heat pump heaters (HP, N = 12) located in the living rooms, and mould growth on the living room and bedroom walls, of 26 New Zealand (NZ) occupied homes was investigated during winter. Two methods were employed to evaluate the potential of mould growth on walls: (i) measurement of daily hyphal growth rate using a fungal detector (encapsulated fungal spores); and (ii) estimation of fungal contamination based on a four level scale visual inspection. The average wall psychrometric conditions were significantly different between the two heater type groups, in both the living rooms and the bedrooms with the UGH user homes being colder and damper than HP user homes. The UGHs were found to be a significant additional source of moisture in the living rooms which dramatically increased the capacity for fungi to grow on wall surfaces. The average daily hyphal growth rates were 4 and 16 times higher in the living rooms and in the bedrooms of the UGH user homes, respectively. Results from both mould detection methods gave good agreement, showing that the use of a fungal detector was an efficient method to predict the potential of mould growth on the inside of the external walls in NZ homes.
- ItemRetrofitting solar air heaters in New Zealand schools – A randomized crossover intervention study(Elsevier B.V, 2024-06-15) Wang Y; Phipps R; Boulic M; Plagmann M; Cunningham C; Guyot GMost New Zealand (NZ) schools rely on natural ventilation and are often inadequately ventilated in winter. NZ school hours typically span from 9 a.m. to 3 p.m. and are well aligned with optimum solar radiation. Existing classrooms could therefore be heated and ventilated using retrofitted solar energy applications. To investigate the suitability of a commercially available solar air heater (SAH) to improve ventilation, a randomized crossover intervention study was conducted in 12 classrooms from six primary schools in Palmerston North, NZ, during the winter of 2014. Typical performance results showed a mean (standard deviation, SD) SAH outlet air temperature of 29.2 (10.4) °C at a mean (SD) velocity of 0.7 (0.3) m·s-1. During most school periods (64–99%) classrooms maintained required thermal comfort. The concurrent use of the extant heaters was reduced, and carbon dioxide levels were improved, lowering exposure for occupants. This study confirmed that retrofitting SAHs contributed to improved classroom ventilation, increased thermal comfort and reduced energy use. Optimising performance would require design improvements to improve airflow in order to comply with NZ ventilation and indoor air quality requirements for schools.
- ItemReview of the thermal efficiency of a tube-type solar air heaters(Elsevier B.V., 2024-05-11) Pardeshi PS; Boulic M; van Heerden AH; Phipps R; Cunningham CWThere is an urgent need to provide evidence that solar air heaters can be effective for heating and ventilating low-rise buildings. Solar air heaters are devices that can convert solar energy into thermal energy for moderate and low-temperature applications such as space heating, preheating, crop drying, and the food industry. However, its efficiency is low due to the low heat transfer coefficient between the absorber and the flowing air, but they are also simple to construct and operate as there is low-risk leakage of heat transfer liquids. The two main types of solar air heaters are flat plate and tube-type. To date, flat plate solar air heaters have received the most attention in the research literature, but evidence of the efficiency gains from using tube-type solar air heaters is growing. The study aims to provide up-to-date information on tube-type solar air heaters, which will help advance the development and uptake of solar air heaters. The research showed that thermal efficiency gains could be achieved by altering the design of the solar air heater including different artificial roughness geometries inside the tubes, integrating solar thermal energy systems, application of coatings or reflectors inside the solar air heaters, or using evacuated tubes and micro heat pipe array systems. This literature study showed that evacuated tubes and micro heat pipe array systems have higher thermal efficiency than other techniques. Based on the detailed discussion of various techniques for improving the thermal efficiency of solar air heaters, a new roughness geometry was proposed.
- ItemThe built environment - A missing ‘cause of the causes’ of non- communicable diseases(MDPI AG, 2016) Walls K; Boulic M; Boddy JWDThe United Nations “25 × 25 Strategy” of decreasing non-communicable diseases (NCDs), including cardiovascular diseases, diabetes, cancer and chronic respiratory diseases, by 25% by 2025 does not appear to take into account all causes of NCDs. Its focus is on a few diseases, which are often linked with life-style factors with “voluntary” “modifiable behavioral risk factors” causes tending towards an over-simplification of the issues. We propose to add some aspects of our built environment related to hazardous building materials, and detailed form of the construction of infrastructure and buildings, which we think are some of the missing causes of NCDs. Some of these could be termed “involuntary causes”, as they relate to factors that are beyond the control of the general public.