Microplastics in Water Treatment Plants

The growing of the consumer culture has contributed to the massive rising of microplastic in environmental samples. Several studies have shown that the rise in microfibers and microplastics has to do with common household items such as facewash, toothpaste, clothing, and cleaning supplies. In this research, we began by collecting samples from a North Georgia drinking water plant. Fluorescent orange polyethylene microspheres, 600-710-micron, were added to assess the extraction methodology. These microspheres were extracted using the National Oceanic and Atmospheric Administration (NOAA) procedure. Filtered samples were analyze on filter paper underneath a 3.5X-180X Zoom Stereo Microscope. The filter paper was labeled by quadrants to be able to analyze the samples easier and more efficiently. Then, natural organics were differentiated from the added polyethylene microspheres and the existing microplastics from the sample. We have found a large number of microplastics/microfibers from the environmental sludge samples that were collected. Additionally, not all the microspheres that we embedded in the samples were accounted for, indicating that the extraction procedure damages the microplastics within the sample. From this, we will further assess more samples with microplastics in order to further our research, as well as compare various extraction methods

Evaluation of Lubricant Properties and Refrigerant Interaction

Lubricant selection for compressors used in the HVAC&R industry is typically tied to the refrigerant and subsequent properties understood to be desirable for effective system operation. Over the years refrigerants have changed, and with each change there has been a need for the reevaluation of the interaction with lubricants. In some cases, the existing lubricants can be utilized, however, in others, a there has been the need for new lubricants to be developed. Unfortunately, engineers have typically not challenged what constitutes good and have proceeded with outdated values for “good” or “desirable” properties of the lubricant-refrigerant mixture. Or, in some cases, the values have been tightened, not because the system or the industry required it, but rather because the refrigerants with their lubricants have become so “good” that there was not a way to distinguish between offerings. To differentiate products, engineers increased the severity of the tests and tightened the test result specification and that resulted in breaking what is the necessary properties for design. With the introduction of the lower GWP, unsaturated hydrofluorocarbon products (HFOs), hydrocarbons and CO2, the opportunity exists to assess potential changes to lubricant chemistries that still allow for acceptable use in air conditioning and refrigeration applications to offset the inherent instability of the refrigerant molecules, so we must return to an evaluation of what does the system require for durable, efficient operation. This paper will look at what current parameters are valued for a refrigeration lubricant, how these parameters are measured and why they are important. A focus will be put on looking at what is needed to be successful with next generation low GWP refrigerants and some examples of lubricant candidates for various low GWP refrigerants. Studies will be shown that investigate how we make evaluations and how some of the current approaches need to be revisited

Compatibility of R1234yf and R134a and Lubricants used in Automotive Compressors

Understanding the compatibility of system materials with R1234yf, R1234zeE and R134a is critical to long term operation of air conditioning and refrigeration systems. Today\u27s regulatory climate of reporting and eliminating system leaks leaves very little margin of error when approving elastomeric materials to seal internal and external connections over the lifetime of the system. Thermoplastics and polymeric O-ring materials have been tested in accelerated conditions to determine volume change, strength change, extraction of plasticizers or dyes, and compatibility of the lubricant and refrigerant. Results and conclusions are presented in graphical and tabular format along with conclusions on polymeric types are suited continued development as long term system sealing and functional life

Fluctuation-Enhanced Sensing with Commercial Gas Sensors

Abstract: The stochastic component of the sensor signal in commercial semiconductor gas sensors during exposure to different gases has been studied. The resistance fluctuation measurements have been carried out using different concentrations of ethanol, CO, NO x , H 2 and SO 2 in dry synthetic air. The analysis of the stochastic resistance fluctuations in gas sensors during exposure to gases enables an enhanced sensitivity and selectivity. The normalized power spectrum is characteristic for each sensor, and each gas induces a new characteristic power spectrum. In many cases, sensors can be used even for different gases than the gas they were originally designed for