The structure and function of conjunctiva-associated lymphoid tissue in chickens and turkeys

The morphology of conjunctiva-associated lymphoid tissue (CALT) was studied in chickens and turkeys by gross, light microscopic, and electron microscopic techniques. Additional studies, using carbon, iron oxide, and latex beads, characterized particle uptake by CALT and statistically evaluated computerized image analysis findings;Although not present at hatching, CALT developed in the lower eyelid of turkeys and chickens in association with longitudinal conjunctival folds and fissures. During the first week, CALT appeared as lymphoid nodules that expanded conjunctival folds. A statistically significant increase in CALT was demonstrated during the post-hatching period. Fewer isolated nodules were evident in the upper eyelid conjunctiva. Lymphoid nodules were composed of lymphocytes, lymphoblasts, macrophages, and germinal centers. The epithelium was flattened, contained intraepithelial lymphocytes, lacked goblet cells, and formed a lymphoepithelium with a discontinuous basement membrane. Vessels evident at the base of lymphoid nodules had high endothelial cells and adherent intraluminal lymphocytes. In addition, chronic antigenic stimulation induced by bacterial conjunctivitis in turkeys produced hyperplasia in CALT;The capacity for transepithelial particle uptake was verified by light microscopy using carbon, iron oxide, and latex beads. Clustering within subepithelial macrophages was characteristic after uptake. Uptake increased with tracer contact time and was more extensive in older birds. The site of tracer uptake varied with particle size, occurring superficially along lymphoepithelial folds for smaller particles but deeper within fissures for larger particles. Using computerized image analysis, a statistically significant increase in uptake was demonstrated between 5 and 15 minutes of tracer contact time and between 3 and 5 weeks of age;These studies document the similarity in structure and function between CALT and other mucosal lymphoid tissues. Therefore, CALT likely has a role in paraocular and upper respiratory immunity in turkeys and chickens

Impact of Mechanical Ventilation and Indoor Air Recirculation Rates on the Performance of an Active Membrane Energy Exchanger System

As concern for indoor air quality grows, many buildings will likely opt to provide higher rates of outdoor air than would traditionally be specified. This imposes a challenge on air conditioning systems since the latent loads associated with ventilation air are much higher than those associated with recirculated air. Membrane-based technologies, which enable mechanical separation of water vapor from air, have recently emerged as promising candidates for efficiently providing dehumidification, however, limitations remain. To date, most modeling work on these types of systems has focused on 100% outdoor air configurations that employ isothermal dehumidification designs. However, we have proposed a design referred to as the Active Membrane Energy Exchanger (AMX) that integrates cooling and membrane dehumidification into one device (thus non-isothermal) for a range of benefits. This work presents a specific application of the AMX in a system configuration that includes the treatment of both outdoor ventilation air and recirculated air. The system’s performance is analyzed over a broad range of ambient conditions and the effect of ventilation rates on the system performance is studied in detail. This configuration is found to be capable of providing three times the ventilation air of conventional systems with comparable or less energy consumption for the given conditions. Additionally, the optimal membrane module-outlet air temperature is found to be 18-20 ℃. Lastly, a case study using EnergyPlus building simulations shows that this configuration can reduce annual cooling energy requirements by as much as 34% in hot and humid cities for buildings with high latent loads and high ventilation rates

Vapor-selective active membrane energy exchanger for high efficiency outdoor air treatment

As much as 40% of the total load on air conditioning systems can be attributed to condensation dehumidification. However, new water vapor-selective membranes present a unique opportunity to greatly reduce the power requirements for moisture removal by avoiding phase change and have thus been ranked as a top alternative to traditional HVAC systems. To date, however, all such systems have relied on the assumption of constant temperature, even terming the technology “isothermal dehumidification.” This work proposes a membrane-based air cooling and dehumidification approach, referred to as the Active Membrane Energy Exchanger (AMX), which is the first to provide simultaneous, yet decoupled, air cooling and dehumidification. The suggested AMX configuration uses two vapor-selective membrane modules with a water vapor compressor in between them, using the second membrane module to reject vapor into the exhaust stream. Cooling and heating coils in each membrane module channel move heat between the air streams using a vapor compression cycle. A detailed steady-state, thermodynamic model is presented for the AMX integrated within a 100% outdoor air conditioning system. The AMX’s limiting parameters and design considerations like compressor efficiency are systematically analyzed for a broad range of outdoor air conditions and compared against standard and state-of-the-art dedicated outdoor air systems. This new high efficiency approach is found to outperform all other standard and state-of-the-art systems, achieving 1.2–4.7 times the COP over conventional dedicated outdoor air treatment. Lastly, a building simulation case study predicted cooling energy savings as high as 66% in hospital buildings with 100% outdoor systems in hot, humid climates

Vapor-selective active membrane energy exchanger with mechanical ventilation and indoor air recirculation

It is widely known that increasing outdoor air ventilation rates in buildings can help improve indoor air quality and mitigate the spread of diseases. However, cooling and dehumidifying outdoor air requires significantly more energy than treating indoor recirculated air. Recent developments in water vapor-selective membranes, which use a vapor partial pressure gradient to remove water vapor from air, offer a unique opportunity to provide highly efficient dehumidification in HVAC systems that can justify high outdoor air ventilation rates without drastic increases in energy consumption. This work presents an analysis of a novel membrane HVAC system referred to as the Active Membrane Energy Exchanger (AMX), which couples a refrigeration cycle with selective membranes to simultaneously cool and dehumidify air. While past selective membrane dehumidification systems have been isothermal, the AMX is the first to deliberately target non-isothermal operation by combining membrane dehumidification and active heat exchange. A thermodynamic model is developed for the AMX in a system that uses both outdoor air ventilation and indoor air recirculation (AMX-R) to elucidate the limitations around increasing ventilation rates. This study is among the first to consider recirculation for selective membrane processes, rather than only 100% outdoor air. The AMX-R can achieve up to 50% cooling and dehumidification electricity savings in warm and humid climates under current ventilation standards. Furthermore, ventilation rates can be nearly tripled with the AMX-R while consuming similar amounts of energy as conventional HVAC systems. Lastly, the incorporation of EnergyPlus building simulations for 114 US cities shows that the AMX-R has the greatest potential in the southern regions of the US

Managing Humidity in Electronics Using Water Vapor-Selective Membranes

Abstract: As outdoor electronics have become prevalent in every aspect of daily life, handling humidity in them is an emerging issue for reliable devices. As water vapor enters the electronics enclosure, there is a risk of condensation, which could prevent the electronics from functioning and further damage the device. Traditionally, the humidity removal for electronics is usually done by heating the air within the enclosure, which can be energy-intensive and less efficient. Vapor selective membrane systems are promising alternatives for air heating dehumidification as they do not require heating energy for water vapor removal. It allows water vapor transport through the membrane while blocking air. The objective of this research in the spring is to design and assemble electronics enclosures with a vapor selective membrane and sensors to monitor the humidity removal progress. Two designs including a vacuum pump and joule pump will be tested. The expected results are testable prototypes and preliminary test data that prove it is possible to accurately monitor the humidity level both inside and outside the enclosure for future testing

Thermodynamic limits of atmospheric water harvesting

Atmospheric water harvesting (AWH) is a rapidly emerging approach for decentralized water production, but current technology is limited by trade-offs between energy consumption and yield. The field lacks a common basis to compare different AWH technologies and a robust understanding of the performance impacts of water recovery, desorption humidity (for sorbent systems), and realistic component-level efficiencies. By devising a set of unifying assumptions and consistent parameters across technologies, we provide the first fair thermodynamic comparison over a broad range of environmental conditions. Using 2nd law analysis, or least work, we study the maximum efficiency for common open system AWH methods – fog nets, dew plates, membrane-systems, and sorption processes – to identify the process performance limits. We find that the thermodynamic minimum for any AWH process is anywhere from 0× (relative humidity (RH) ≥ 100%) to upwards of 250× (RH \u3c 10%) the minimum energy requirement of seawater desalination. Sorbents have a particular niche in colder (T \u3c 310 K), arid regions (\u3c6 g kg−1). Membrane-systems are best at low relative humidity and the region of applicability is strongly affected by vacuum pumping efficiency. Dew harvesting is best at higher humidity (RH \u3e 40%) and fog harvesting is optimal when super-saturated conditions exist. Increasing efficiency at the component-level, particularly for vacuum pumps and condensers, may be the most promising avenue for improvement. Enabled by peta-scale computing, our findings use geographical and parametric mapping to provide a framework for technology deployment and energy-optimization