A Technique for Rapid Estimation of the Charge Distribution of Submicron Aerosols under Atmospheric Conditions

A portable technique is presented for rapid estimation of the charge distribution of submicron aerosols under atmospheric conditions, using two Differential Mobility Analyzer (DMA) systems in parallel. Simultaneous measurement of the aerosol mobility and size distributions are made by using one DMA with a neutralizer and the other without. An estimate of the aerosol charge is obtained by a fitting procedure, in which the size distribution and an expression for the charge distribution are used to calculate the mobility distribution of the sample. The parameters in the theoretical charge distribution are varied iteratively until the calculated and measured mobility distributions match. Validation was undertaken with separate measurements of ion mobility and concentration used in the charging expression. Results are presented for ambient indoor air, unipolar ion production by an ionizer and downwind of a high-voltage overhead AC powerline.     

Optimization of processing conditions for vacuum frying of high quality fried plantain chips using response surface methodology (RSM)

Optimization of processing conditions (temperature 122 to 136°C, vacuum pressure 9.91 to 19.91 cmHg, and frying time 3 to 9 min) during vacuum frying of plantain chips was investigated using a Box-Behnken experimental design with response surface methodology (RSM). Models for various responses were developed and optimized frying conditions using numerical solutions were established. Optimized vacuum fried samples were compared with atmospheric fried samples based on the concept of equivalent thermal driving force (ETDF). Frying parameters had significant (p<0.05) effects on the moisture content, texture, and color with a coefficient of determination (R ²) for quadratic model responses varying between 0.53 and 0.99. Optimum vacuum frying conditions for plantain chips were a frying temperature of 133°C, vacuum pressure of 9.91 cmHg, and frying time of 6 min based on desirability concepts. Vacuum fried plantain chips had more acceptable sensory properties, based on ETDF values, than atmospheric fried samples.     

A model for the dehydration of waterborne basecoat

In vehicle manufacturing, a common topcoat process sequence is the application of a waterborne basecoat, partial dehydration, application of a solventborne clearcoat, then curing at approximately 150°C. Anecdotal evidence suggests that under “harsh” (high temperature and velocity) dehydration conditions, a skin can be formed, which can trap excess water in the basecoat. Upon curing, the excess water forms vapor that can burst through the topcoat, leading to surface imperfections, termed pinholes or pops. A forward-time center-distance finite difference model, incorporating only diffusion and evaporation and experimentally determined coefficients, was used to simulate the water concentration in the layers of a paint film. Simulations were conducted at constant temperatures (27°C and 82°C) as well as by using temperature traces from a full-size dehydration oven under harsh (82°C) and gentle (54°C) conditions. The model accurately predicted the overall solids content after dehydration. However, in both temperature scenarios, the surface layer water concentration was less at the low temperature for the same overall solids content. This counter-intuitive finding is attributed to the increase in diffusivity with temperature, which allows water to be supplied to the surface faster in the high temperature run in each scenario. Therefore, this simple diffusion-evaporation model is not suitable for simulating water entrapment leading to popping.     

Implementing DOE to study the effect of paint application parameters, film build, and dehydration temperature on solvent pop

This research investigated popping when automotive clearcoat was applied over waterborne basecoats using design of experiments (DOE). The study was conducted using melamine crosslinked acrylic latex basecoat and acrylic acid/epoxy clearcoat. The focus of the project was directed toward the paint application and dehydration stages. The study was conducted in four phases. In Phase 1, three paint application parameters, flow rate (FR), atomizing air (AA), and distance of the applicator tip from the substrate (D), were investigated. In Phase 2, FR and target distance were investigated in relation to popping while keeping other parameters as well as film build constant. In Phase 3, the effect of film build on popping was investigated by selecting three levels of film build. Phase 4 was focused on the possible effect of dehydration oven temperature on popping. Results indicated that FR does not affect popping directly. However, it significantly affects the film build. Both film build and dehydration oven temperature were found significant in relation to popping occurrences. This work suggests that dehydration oven temperature and film build affect solvent popping. Although this study identified the significant factors causing waterborne basecoat popping, conditions for a pop-free paint surface were not established.     

Low carbon heating and older adults: comfort,cosiness and glow

Policies to decarbonize heat provision involve the diffusion of low carbon thermal technologies (e.g. ground-source heat pumps and wood pellet boilers). In domestic buildings, such efforts presume the compatibility of novel technologies with practices of home-making, in terms of comfort, cosiness and sociability. However, research on engagement with low carbon technologies post-installation is limited, particularly with older adults, a growing social group in an ageing society. This study explores how older adults living with low carbon thermal technologies represent thermal comfort, drawing on in-depth interviews in diverse UK home environments (owner-occupied and rented; extra-care, sheltered and care homes; urban and rural). Findings indicate that cosiness and glow are highly valued by and for older adults, and achieved in diverse ways that may run counter to policy goals. In owner-occupied, rural homes, wood-burning stoves were retained after installation of under-floor heating/heat pumps to provide a visible glow and hospitality to guests. In care homes, fake fireplaces provide cosiness and glow without compromising concerns about risk. The research suggests that presumed emissions savings from the deployment of low carbon heating technologies may be overestimated, as home-making practices lead to the supplementing of these devices to provide comfort, cosiness and sociability.