Development of an Integrated Residential Heating, Ventilation, Cooling, and Dehumidification System for Residences

The Need and the Opportunity Codes such as ASHRAE 90.2 and IECC, and programs such as Energy Star and Builders Challenge, are causing new homes to be built to higher performance standards. As a result sensible cooling loads in new homes are going down, but indoor air quality prerogatives are causing ventilation rates and moisture loads to increase in humid climates. Conventional air conditioners are unable to provide the low sensible heat ratios that are needed to efficiently cool and dehumidify homes since dehumidification potential is strongly correlated with cooling system operating hours. The project team saw an opportunity to develop a system that is at least as effective as a conventional air conditioner plus dehumidifier, removes moisture without increasing the sensible load, reduces equipment cost by integrating components, and simplifies installation. Project Overview Prime contractor Davis Energy Group led a team in developing an Integrated Heating, Ventilation, Cooling, and Dehumidification (I-HVCD) system under the DOE SBIR program. Phase I and II SBIR project activities ran from July 2003 through December 2007. Tasks included: (1) Mechanical Design and Prototyping; (2) Controls Development; (3) Laboratory and Field Testing; and (4) Commercialization Activities Technology Description. Key components of the prototype I-HVCD system include an evaporator coil assembly, return and outdoor air damper, and controls. These are used in conjunction with conventional components that include a variable speed air handler or furnace, and a two-stage condensing unit. I-HVCD controls enable the system to operate in three distinct cooling modes to respond to indoor temperature and relative humidity (RH) levels. When sensible cooling loads are high, the system operates similar to a conventional system but varies supply airflow in response to indoor RH. In the second mode airflow is further reduced, and the reheat coil adds heat to the supply air. In the third mode, the reheat coil adds additional heat to maintain the supply air temperature close to the return air temperature (100% latent cooling). Project Outcomes Key Phase II objectives were to develop a pre-production version of the system and to demonstrate its performance in an actual house. The system was first tested in the laboratory and subsequently underwent field-testing at a new house in Gainesville, Florida. Field testing began in 2006 with monitoring of a 'conventional best practices' system that included a two stage air conditioner and Energy Star dehumidifier. In September 2007, the I-HVCD components were installed for testing. Both systems maintained uniform indoor temperatures, but indoor RH control was considerably better with the I-HVCD system. The daily variation from average indoor humidity conditions was less than 2% for the I-HVCD vs. 5-7% for the base case system. Data showed that the energy use of the two systems was comparable. Preliminary installed cost estimates suggest that production costs for the current I-HVCD integrated design would likely be lower than for competing systems that include a high efficiency air conditioner, dehumidifier, and fresh air ventilation system. Project Benefits This project verified that the I-HVCD refrigeration compacts are compact (for easy installation and retrofit) and can be installed with air conditioning equipment from a variety of manufacturers. Project results confirmed that the system can provide precise indoor temperature and RH control under a variety of climate conditions. The I-HVCD integrated approach offers numerous benefits including integrated control, easier installation, and reduced equipment maintenance needs. Work completed under this project represents a significant step towards product commercialization. Improved indoor RH control and fresh air ventilation are system attributes that will become increasingly important in the years ahead as building envelopes improve and sensible cooling loads continue to fall. Technologies like I-HVCD will be instrumental in meeting goals set by Building America and other programs to reduce energy use while improving the indoor environment. Next Steps The following steps are needed to bring the product to commercialization: (1) Value engineering to reduce costs; (2) Addition of zoning capability to improve marketability; (3) Fabrication and testing of additional prototypes; and (4) Identification of a manufacturer. Initial efforts to interest large air conditioner manufacturers has shown some interest, but the preferred path to market may be to employ a boutique manufacturer that markets to HVAC contractors. Distribution of the results of this work will improve opportunities for attracting manufacturers. Additional funding is needed to prepare the product for this final step

Effects of Temperature and Moisture on Sheet Molding Compounds

A summary is given on the effects of moisture and temperature on the properties of chopped fiber reinforced sheet molding compounds. The properties surveyed include tensile strength and modulus, compression strength and modulus, shear strength and modulus, flexural strength and modulus, fatigue, creep, vibration damping, moisture absorption characteristics, and thermal expansion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68648/2/10.1177_073168448300200201.pd

Environmental Effects on Glass Fiber Reinforced Polyester and Vinylester Composites

The effects of environment on glass fiber reinforced polyester and vinylester composites immersed in liquids and in humid air were investi gated. Tests were performed at temperatures 23 C and 93 C with the materials exposed to humid air at 50 and 100 percent relative humidities, and to five different liquids: saturated salt water, No. 2 diesel fuel, lubrica ting oil, antifreeze, and indolene. Changes in weight, ultimate tensile strength, tensile modulus, short beam shear strength, and shear modulus were measured over a six month period, and the effects of the environment on these parameters were assessed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66642/2/10.1177_002199838001400304.pd

Expansion in perfect groups

Let Ga be a subgroup of GL_d(Q) generated by a finite symmetric set S. For an integer q, denote by Ga_q the subgroup of Ga consisting of the elements that project to the unit element mod q. We prove that the Cayley graphs of Ga/Ga_q with respect to the generating set S form a family of expanders when q ranges over square-free integers with large prime divisors if and only if the connected component of the Zariski-closure of Ga is perfect.Comment: 62 pages, no figures, revision based on referee's comments: new ideas are explained in more details in the introduction, typos corrected, results and proofs unchange

An Oscillatory Contractile Pole-Force Component Dominates the Traction Forces Exerted by Migrating Amoeboid Cells

We used principal component analysis to dissect the mechanics of chemotaxis of amoeboid cells into a reduced set of dominant components of cellular traction forces and shape changes. The dominant traction force component in wild-type cells accounted for ~40% of the mechanical work performed by these cells, and consisted of the cell attaching at front and back contracting the substrate towards its centroid (pole-force). The time evolution of this pole-force component was responsible for the periodic variations of cell length and strain energy that the cells underwent during migration. We identified four additional canonical components, reproducible from cell to cell, overall accounting for an additional ~20% of mechanical work, and associated with events such as lateral protrusion of pseudopodia. We analyzed mutant strains with contractility defects to quantify the role that non-muscle Myosin II (MyoII) plays in amoeboid motility. In MyoII essential light chain null cells the polar-force component remained dominant. On the other hand, MyoII heavy chain null cells exhibited a different dominant traction force component, with a marked increase in lateral contractile forces, suggesting that cortical contractility and/or enhanced lateral adhesions are important for motility in this cell line. By compressing the mechanics of chemotaxing cells into a reduced set of temporally-resolved degrees of freedom, the present study may contribute to refined models of cell migration that incorporate cell-substrate interactions

Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

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Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems