High-volume low-speed fan for cooling of a large enclosed space

A ceiling fan is a commonly used mechanical device for promoting airflow inside an enclosed space, for thermal comfort purposes. However, it is difficult to clean and maintain, noisy and sometimes can be dangerous to occupants. Recently, a high-volume low-speed fan (HVLS) was introduced as an alternative device to provide better air movement at a lower energy cost. This study aims to compare the distribution of airflow velocity produced by a single HVLS fan and that produced by two ceiling fans inside a room, using computational fluid dynamic (CFD) method. Two simplified models of two similar rooms were developed using commercial CFD software. One is furnished with an HVLS fan and the other with two ceiling fans. Steady-state flow simulations were performed on the CFD models using a Spalart-Allmaras turbulence airflow model and adopting a moving reference frame (MRF) technique. The CFD models were validated based on experimental data obtained from the literature. It was found that for a single HVLS fan operating at a rotational speed of 140 RPM, the average airflow velocity on a horizontal plane at 1.1 m height from the floor is around 0.87 m/s. This value falls within the range stated in the ASHRAE-55 standard for good thermal comfort. For the room furnished with two ceiling fans operating at the same rotational speed, the average airflow velocity on the similar horizontal plane is around 0.19 m/s, which is outside the limit specified in the ASHRAE-55 standard. But when the two ceiling fans were operated at a rotational speed of 300 RPM, the average airflow velocity on the plane increases to 0.42 m/s, which satisfies the ASHRAE Standard-55 requirement. These findings suggest that a single HVLS fan would provide a more desirable air movement inside a confined space thereby would promote a much better feeling of thermal comfort to the occupants, as compared to the use of two ceiling fans operating at a much higher rotational speed

An analysis of the quality of life among diabetic foot ulcer patients in Kuantan, Pahang

Introduction: Foot ulcer is one of the most serious complications associated with diabetes mellitus that mat resulted in a disability and impairment of health related quality of life. Materials and Methods: The main objective of this cross-sectional study was to determine the factors adversely associated with quality of life among diabetic foot ulcer patients. Diabetic patients with evidence of diabetic foot ulcer attending outpatient orthopaedics and general surgical clinic of Hospital Tengku Ampuan Afzan were recruited into this study. A set of validated SF-36 questionnaire was employed to evaluate the health-related quality of life for each patient. This study was registered with the National Medical Research Register (NMRR registration no. 17-1520-36332). Results: There is a slightly higher proportion of female among the 104 respondents. Its prevalence is most pronounces in the lower income group. Majority presented with Wagner stage 2 and 3. Amputation has been performed in 54% of these patients. Physical health score fair worse than mental health. Age, low socioeconomic status, presence of comorbidities, major amputation, ulcer at the forefoot and wheelchair usage associated with an adverse effect on the physical health aspect in these patients. Interestingly, smoker seems to score better on the mental health aspect of the quality of life. Conclusion: Diabetic foot ulcer affected physical health aspect much more than mental health aspect within the context of the quality of life