Development and laboratory performance evaluation of a personal cascade impactor

This paper presents the design and laboratory evaluation of a personal cascade impactor. The system is compact, lightweight, and uses a single battery-operated sampling pump. It operates at a flow rate of 5 L/min and consists of four impaction stages, each equipped with slit-shaped acceleration nozzles, and a backup filter. The impactor was calibrated using polydisperse particles. The 50% cut points of the four stages were 9.6, 2.6, 1.0, and 0.5 microm, respectively. The backup filter is placed downstream of the fourth stage and is used to collect the particles with an aerodynamic diameter smaller than 0.5 microm (dp < 0.5 microm). The major feature of this novel sampler is its ability not only to fractionate the particles with an aerodynamic diameter smaller than 10 microm to the various size fractions, but also to collect them onto relatively small polyurethane foam substrates without using adhesives. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found to be insignificant. Interstage losses of particles smaller than 0.5 microm were less than 10%; for fine particles, less than 5%; and for coarse particles, less than 12%. The pressure drop across the four stages and the backup filter were 0.015 kPa (0.153 cm H2O),0.025 kPa (0.255 cm H2O), 0.274 kPa (2.794 cm H2O), 0.323 kPa (3.294 cm H2O), and 0.370 kPa (3.773 cm H2O), respectively. Particles can be easily recovered from the foam substrates using aqueous extraction.     

Evaporative Cooling of Water in a Small Vessel Under Varying Ambient Humidity

Evaporative cooling of water in a small porous clay vessel was studied under controlled humidity conditions. In steady-state experiments performed at an ambient temperature of 23 °C, the cooling effect increased from 4.7 to 8.3 °C as the ambient relative humidity decreased from 60 to 15%. External heat and mass transfer coefficients, estimated from the steady-state measurements, were used in mathematical models to predict the experimentally observed transient temperature variation of the water under ramp changes of the ambient relative humidity. With a prototypical cool chamber containing water tested in Kolkata, India under an ambient temperature of 34.5–35 °C, the cooling effect reached a maximum of 7 °C between 3 and 3:30 PM and then declined to 4.5 °C around 6 PM.     

Unravelling the molecular mechanism of mutagenic factors impacting human health

Environmental Science and Pollution Research - Environmental mutagens are chemical and physical substances in the environment that has a potential to induce a wide range of mutations and generate...     

Condenser cooling technologies for concentrating solar power plants: a review

Environment, Development and Sustainability - Selection of condenser cooling technology can affect the financial as well as technical viability of concentrating solar power (CSP) plants. Detailed...