Results for “Building HVAC control”

NASA NTRS2005

Fault Diagnosis in HVAC Chillers

Modern buildings are being equipped with increasingly sophisticated power and control systems with substantial capabilities for monitoring and controlling the amenities. Operational problems associated with heating, ventilation, and air-conditioning (HVAC) systems plague many commercial buildings, often the result of degraded equipment, failed sensors, improper installation, poor maintenance, and improperly implemented controls. Most existing HVAC fault-diagnostic schemes are based on analytical models and knowledge bases. These schemes are adequate for generic systems. However, real-world systems significantly differ from the generic ones and necessitate modifications of the models and/or customization of the standard knowledge bases, which can be labor intensive. Data-driven techniques for fault detection and isolation (FDI) have a close relationship with pattern recognition, wherein one seeks to categorize the input-output data into normal or faulty classes. Owing to the simplicity and adaptability, customization of a data-driven FDI approach does not require in-depth knowledge of the HVAC system. It enables the building system operators to improve energy efficiency and maintain the desired comfort level at a reduced cost. In this article, we consider a data-driven approach for FDI of chillers in HVAC systems. To diagnose the faults of interest in the chiller, we employ multiway dynamic principal component analysis (MPCA), multiway partial least squares (MPLS), and support vector machines (SVMs). The simulation of a chiller under various fault conditions is conducted using a standard chiller simulator from the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). We validated our FDI scheme using experimental data obtained from different types of chiller faults.

Choi, Kihoon↗

NASA NTRS1976

Energy conservation and analysis and evaluation

The survey assembled and made recommendations directed at conserving utilities and reducing the use of energy at the Slidell Computer Complex. Specific items included were: (1) scheduling and controlling the use of gas and electricity, (2) building modifications to reduce energy, (3) replacement of old, inefficient equipment, (4) modifications to control systems, (5) evaluations of economizer cycles in HVAC systems, and (6) corrective settings for thermostats, ductstats, and other temperature and pressure control devices.

Source record↗

NASA NTRS1978

Site selection feasibility for a solar energy system on the Fairbanks Federal Building

A feasibility study was performed for the installation of a solar energy system on the Federal Building in Fairbanks, Alaska, a multifloor office building with an enclosed parking garge. The study consisted of determining the collectable solar energy at the Fairbanks site on a monthly basis and comparing this to the monthly building heating load. Potential conventional fuel savings were calculated on a monthly basis and the overall economics of the solar system applications were considered. Possible solar system design considerations, collector and other system installation details, interface of the solar system with the conventional HVAC systems, and possible control modes were all addressed. Conclusions, recommendations and study details are presented.

Source record↗

NASA NTRSDate not supplied

Lessons Learned From Designing and Building Low Organic Outgassing Cleanrooms for NASA OSIRIS-REx and Hayabusa2 Curation Facility

NASA Johnson Space Center Astromaterials Acquisition and Curation Office completed construction and commissioning of the OSIRIS-REx and Hayabusa2 cleanroom laboratory suites along with new precision cleaning and advanced curation laboratories consisting of ISO Class 5, 6, and 7 cleanrooms. The new curation facilities are designed for initial receiving, basic characterization, curation processing, and preliminary examination of carbonaceous asteroidal material. The facilities are also designed to enable long-term pristine sample storage to preserve the scientific integrity of each sample to enable future research by the international science community. The scientific study of organics is critical for both missions. The OSIRIS-REx mission instituted a stringent contamination control plan for low organics. Given these mission requirements and long-term storage preservation requirements, cleanroom construction materials were carefully selected to not hinder the scientific search for amino acids and the study of organics in the samples. Cleanroom candidate construction materials were researched for the HVAC system, floors, walls, ceiling, and plenum areas. The team chose several candidate materials that were further tested for their specific outgassing characteristics using ASTM E-595 per ASTM E-2312. The information gained provided the foundation for the final design selection of the cleanroom materials. While material selection is important before and during the facility design phase, the construction phase is where these choices are implemented by the prime construction contractor through final product and material submittals. These submittals are the last check point and changes are often submitted due to engineering/construction conflicts, especially when renovating an existing building. Any new material or equipment/product change must be identified and scrutinized for low particulate shedding and outgassing properties. In some cases, quick testing of new material is required, and compromises must be made in real-time. Careful selection and implementation of cleanroom materials significantly reduced organic and inorganic contamination beyond normal cleanroom baselines.

astromaterials curation↗

NASA NTRSDate not supplied

Lessons Learned From Designing and Building Low Organic Outgassing Cleanrooms for NASA OSIRIS-REx and Hayabusa2 Curation Facility

NASA Johnson Space Center Astromaterials Acquisition and Curation Office completed construction and commissioning of the OSIRIS-REx and Hayabusa2 cleanroom laboratory suites along with new precision cleaning and advanced curation laboratories consisting of ISO Class 5, 6, and 7 cleanrooms. The new curation facilities are designed for initial receiving, basic characterization, curation processing, and preliminary examination of carbonaceous asteroidal material. The facilities are also designed to enable long-term pristine sample storage to preserve the scientific integrity of each sample to enable future research by the international science community. The scientific study of organics is critical for both missions. The OSIRIS-REx mission instituted a stringent contamination control plan for low organics. Given these mission requirements and long-term storage preservation requirements, cleanroom construction materials were carefully selected to not hinder the scientific search for amino acids and the study of organics in the samples. Cleanroom candidate construction materials were researched for the HVAC system, floors, walls, ceiling, and plenum areas. The team chose several candidate materials that were further tested for their specific outgassing characteristics using ASTM E-595 per ASTM E-2312. The information gained provided the foundation for the final design selection of the cleanroom materials. While material selection is important before and during the facility design phase, the construction phase is where these choices are implemented by the prime construction contractor through final product and material submittals. These submittals are the last check point and changes are often submitted due to engineering/construction conflicts, especially when renovating an existing building. Any new material or equipment/product change must be identified and scrutinized for low particulate shedding and outgassing properties. In some cases, quick testing of new material is required, and compromises must be made in real-time. Careful selection and implementation of cleanroom materials significantly reduced organic and inorganic contamination beyond normal cleanroom baselines.

astromaterials curation↗

NASA NTRS2015

Layered Thermal Insulation Systems for Industrial and Commercial Applications

From the high performance arena of cryogenic equipment, several different layered thermal insulation systems have been developed for industrial and commercial applications. In addition to the proven areas in cold-work applications for piping and tanks, the new Layered Composite Insulation for Extreme Environments (LCX) has potential for broader industrial use as well as for commercial applications. The LCX technology provides a unique combination of thermal, mechanical, and weathering performance capability that is both cost-effective and enabling. Industry applications may include, for example, liquid nitrogen (LN2) systems for food processing, liquefied natural gas (LNG) systems for transportation or power, and chilled water cooling facilities. Example commercial applications may include commercial residential building construction, hot water piping, HVAC systems, refrigerated trucks, cold chain shipping containers, and a various consumer products. The LCX system is highly tailorable to the end-use application and can be pre-fabricated or field assembled as needed. Product forms of LCX include rigid sheets, semi-flexible sheets, cylindrical clam-shells, removable covers, or flexible strips for wrapping. With increasing system control and reliability requirements as well as demands for higher energy efficiencies, thermal insulation in harsh environments is a growing challenge. The LCX technology grew out of solving problems in the insulation of mechanically complex cryogenic systems that must operate in outdoor, humid conditions. Insulation for cold work includes equipment for everything from liquid helium to chilled water. And in the middle are systems for LNG, LN2, liquid oxygen (LO2), liquid hydrogen (LH2) that must operate in the ambient environment. Different LCX systems have been demonstrated for sub-ambient conditions but are capable of moderately high temperature applications as well.

thermal conductivity↗