Performance evaluation of a chimney solar dryer for Habanero pepper (Capsicum chinense Jacq)

Habanero pepper (Capsicum chinense Jacq) is cultivated predominantly in the Volta, Central and Ashanti regions of Ghana and commonly utilised in  most local dishes. Majority of consumers prefer the dried form of the pepper. However, farmers are usually confronted with the challenge of  obtaining low-cost, locally fabricated dryers that can efficiently dry agricultural produce while mitigating quality and safety concerns. In this study, a model of the newly designed chimney solar dryer by the Horticulture Innovation laboratory of the University of California, Davis, in the United States of America, for crop drying in developing countries was constructed and its performance evaluated in comparison to open sun drying. Habanero pepper was used as a test crop. Subsequently, microbial analysis was carried out on the dried products. The mean chimney dryer temperature (46.4°C) was found to be higher than the ambient temperature (36.2°C). The relative humidity in the chimney solar dryer and the ambient ranged from 25% to 68% and 26% to 83%, respectively. During the period of the drying experiment, mean maximum solar insolation of 823.18 W/m2 was  recorded at 11.30 am while a mean minimum solar insolation of 107.84 W/m2 was recorded at 4.30 pm. The solar-dried and sun-dried pepper  recorded total drying time of 35 h and 55 h respectively. The mean performance coefficient of the chimney solar dryer was determined to be 1.21 which gives an indication of a high dryer performance. The mean yeasts and moulds counts of the solar-dried and sun-dried pepper were 4.30 x 104 cfu/g and 2.52 x 105 cfu/g, respectively. Also, the Staphylococcus aureus and Escherichia coli counts were <10 cfu/g for samples in both drying media. In conclusion, the chimney solar dryer was found to have performed better than open sun drying with shorter drying time and better qualityof the dried product. Key words: chimney, habanero pepper, open sun drying, performance, quality, solar drye

Simplifying the process to perform air temperature and UHI measurements at large scales: Design of a new APP and low-cost Arduino device

The main purpose of Urban Heat Island (UHI) studies and the monitoring of ambient temperatures at large scales is to gather temperature information in a certain area, so as to understand temperature heterogeneity and its drivers or detect locations that lack thermal comfort. However, these studies originate mostly from some research projects, with sufficient budget and manpower to carry out the measurements and the necessary calculations. Thus, there is a scarcity of air temperature information, making it difficult to implement appropriate mitigation actions worldwide. The present work aims to greatly simplify the process to monitor air temperatures and carry out UHI estimations through mobile transects. This is done by introducing the design of a low-cost device and a new APP, which performs automatically most necessary UHI calculations. A web tool based on the Inverse Distance Weighting interpolation method is also included to obtain heat maps. The methodology is illustrated using case studies in Seville (Spain) and New York city (USA). By introducing a straightforward and reproducible methodology, we aim to open the path for a more widespread availability of ambient temperature data anywhere in the world, without the need for costly equipment and many hours of dedication by the researcher

Prototyping of Environmental Kit for Georeferenced Transient Outdoor Comfort Assessment

Environmental data acquisition tools are broadly used for climate monitoring and urban comfort assessment followed by data mining and sensing techniques for putting into evidence the relationship between environmental qualities of urban spaces and human well-being. Within this context, an environmental toolkit is a fundamental tool to evaluate transient outdoor comfort. This study explains the prototyping and validation of a mobile environmental sensor kit. The results show the prototype has reasonable accuracy despite its affordability with respect to industrial sensors

Effect of exposure on the erodibility of intertidal mudflats

Sediments on intertidal flats are exposed during low tides. Under the effect of exposure, the water content of sediments decreases because of the evaporation process, which alters the erosive behaviour of cohesive sediments, and therefore changes the patterns of erosion/accretion on intertidal flats. Consequently, exposure indirectly affects the intertidal morphology. An understanding of how exposure alters the erodibility of sediment on intertidal flats is critical to predicting the resilience of intertidal zones into the future during which sea-level rise is believed to exacerbate erosion in low-lying areas. Sediments were collected from an intertidal mudflat in the Firth of Thames, New Zealand in different seasons from 2017 to 2019 for laboratory experiments. Two experiments (Exp. 1 and Exp. 2) were set up in order to explore the effect of exposure including air temperature and exposure duration on erodibility of cohesive sediments. The EROMES device was used to measure the erosion potential of sediment (erosion threshold, Ƭᵣ N m⁻² and erosion rate, ER g m⁻² s⁻¹). Exp. 1 investigated erodibility of sediments exposed to a wide range of temperatures (controlled at 0, 8, 25 and 40°C) for 6 h. Meanwhile, Exp. 2 was designed to examine the effect of exposure duration on erodibility. In this experiment, a systematically-changed exposure duration (6 h, 1, 4 and 10 d) was used to mimic a wide range of exposure that might happen on an intertidal flat during a year (set to mimic the Firth of Thames field site). Experimental results indicated that erosion resistance of sediments significantly increased (increased Ƭᵣ, and decreased ER) corresponding to decreased water content after exposure. The higher the air temperature and the longer the exposure duration, the more stable the sediments were. For instance, the water content of exposed sediments decreased by 1.01 to 1.78 times, a rate which was a function of increasing temperature. The Ƭᵣ of exposed experiments was 1.2 to 2.2 times higher, whereas ER decreased 1.2 to 6.2 times. After 10 d, exposure increased Ƭᵣ by 1.7 to 4.4 times and decreased ER by 11.6 to 21.5 times compared with 6 h of exposure. Semi-empirical models fitted datasets from Exp.1 and Exp. 2 were used to predict the variations of Ƭᵣ and ER as functions of air temperature, T (°C) and exposure duration, D (h). These semi-empirical models were used to extend a Delft3D numerical model to test the effect of exposure on intertidal mudflat profiles and development of tidal channel networks. Model results indicated that exposure enhanced the more flat-topped shape of intertidal mudflats. Higher air temperature resulted in stronger effects on bed level change. For example, for the case of 40°C, bed level built up by 0.039m after one year of model time. Regarding the development of channel networks on intertidal mudflats, the exposure effect tended to create denser and deeper channel networks compared to model runs without the exposure effect. Our findings, therefore, contribute to the prediction of the intertidal morphology development, which will help to understanding the resilience of tidal flats and salt marshes in future under the effect of sea-level rise and global warming