This paper presents a comprehensive model for advanced membrane-based absorber components accounting for three separate fluid streams, one of them providing internal cooling, with complex flow patterns. The model was implemented with various liquid desiccants and their properties (including LiCl, CaCl2, and [emim][OMS] ionic liquid [IL]). The model has been validated using data from two laboratory prototype absorbers, one with CaCl2 as the working fluid and one with an IL as the working fluid. Entropy analysis was further carried out to verify the model and understand effect of internal cooling on the entropy variation of three fluid streams. The developed model and codes are expected to enable detailed configuration optimization and provide in-depth understanding of three-fluid heat and mass exchanger (HMX) performance. The paper also describes parametric studies of the HMX components in utilizing the latent heat removed in space cooling to heat water and numerically explores the unique benefit of its application in a semi-open absorption heat pump water heater. The results show that a single three-fluid HMX has the potential to achieve simultaneous dehumidification and water heating efficiently at cost effectiveness, particularly in hot and humid climates.

Current natural gas condensing furnaces generate substantial acidic condensate and SOx/NOx/CO/HC/methane emissions, causing long- term environment issues related to air, water and soil. Acidic condensate occurs when flue gases within the furnaces cool down below the dew points of acidic gases, which upon condensation, combine with water vapor to produce acidic solutions. The acidic condensate causes serious corrosion and fouling problems in natural gas condensing furnaces. This paper presents a novel solution to use an advanced adsorption technology based on monolithic acidic gas trap (AGT) adsorbers for SOx trapping, NOx redox, and formic acid/CO/HC/methane oxidation, enabling a new condensing natural gas furnace with ultra-clean flue gas and neutral condensate. When the AGT adsorber is appropriately integrated with natural gas furnaces, the acidic gases of SOx, NOx and formic gas/CO/HC will be continuously adsorbed, redoxed or oxidized, respectively, from the flue gas during a regular heating season, except for occasional regeneration activities for SOx trapping. In the paper, we present results from a prototype furnace employing the novel AGT component, which enables a pH of the condensate =7, NOx emissions of 1-2 nanograms/joule and an annual fuel utilization efficiency (AFUE) of 96%, providing a cost-effective technology for condensing furnaces that is eco-friendly to the environment.

Advanced internally-cooled membraned-based heat and mass exchangers (HMX), which accounts for three separate fluid streams, are capable of utilizing the sensible and latent heat removed from space cooling to heat water. The technology provides a unique approach of enhancing the efficiency and cost effectiveness of future HVAC equipment. This paper aims to numerically identify and understand the impact of geometric size, operation conditions, and membrane properties on the overall effectiveness of three-fluid HMXs. The simulations are based on an ORNL in-house open-source HMX model which is capable of simulating such three-fluid HMX components for various flow patterns. The results are expected to enable detailed configuration evaluation and provide in-depth understanding of optimal three-fluid HMX performance at cost effectiveness.

A preliminary analysis has been conducted to analyze the performance of heat pump water heater which uses CO2 as refrigerant. The model to predict the performance was developed and calibrated based on the experimental data of an existing HPWH using CO2 refrigerant. The model was then used to run a parametric analysis where factors such as water supply temperature, water circulation rate, tank stratification, and condenser configurations were considered. The performance of a commercial CO2 system was compared with a similar system based on R-134a as the refrigerant. For comparable performance, the compressor size and the tube-in-tube heat exchanger (condenser/gas cooler) size have been compared for CO2 and R134a based systems. The impact of water circulation rate on the water temperature stratification in the tank, an essential requirement for higher performance for CO2 HPWH systems, has been investigated.

This paper presents a comprehensive simulation model for advanced membrane-based heat and mass exchanger (HMX) components which account for three separate fluid streams with complex flow patterns. The model was implemented with various liquid desiccants and their properties (including LiCl, CaCl and ionic liquid (IL)). Preliminary model validation is presented using data from a laboratory prototype absorber. The paper also presents implementation of the model into a sorption system modeling platform and analyzes potential benefit analysis of the HMX component in utilizing the sensible and latent heat removed in space cooling to heat water. The developed model and codes are expected to enable detailed optimization studies and identify novel configurations for the three-fluid HMX maximum performance and cost effectiveness.

The Heating, Ventilation, Air-Conditioning and Refrigeration (HVAC&R) industry is currently transitioning away from high global warming potential (GWP) hydrofluorocarbon (HFC) refrigerants. However, many lower-GWP alternatives are flammable. Current safety codes restrict use of all flammable refrigerants; revision of the codes is needed to facilitate wider use of flammable alternatives. Hence, information is needed to enable reliable estimates of safe charge limits for flammable refrigerant options for different HVAC&R applications. A reduced-order model (ROM) was developed and validated to help estimate safe charge limits based on computational fluid dynamics (CFD) simulations of refrigerant releases in a single room for a range of parameters. Validation of the ROM vs. the CFD results showed good general agreement for mean refrigerant concentration. The normalized mean bias error (NMBE) was 0.67% with a maximum error of 15%.

The commercial integrated heat pump with thermal storage (AS-IHP) offers significant energy saving over a baseline heat pump with electric water heater. The saving potential is maximized when the AS-IHP serves coincident high water heating and high space cooling demands. A previous energy performance analysis showed that the AS-IHP provides the highest benefit in the hot-humid and hot-dry/mixed dry climate regions. Analysis of technical potential energy savings for these climate zones based on the BTO Market calculator indicated that the following commercial building market segments had the highest water heating loads relative to space cooling and heating loads education, food service, health care, lodging, and mercantile/service. In this study, we focused on these building types to conservatively estimate the market potential of the AS-IHP. Our analysis estimates maximum annual shipments of ~522,000 units assuming 100% of the total market is captured. An early replacement market based on replacement of systems in target buildings between 15 and 35 years old was estimated at ~136,000 units. Technical potential energy savings are estimated at ~0.27 quad based on the maximum market estimate, equivalent to ~13.9 MM Ton CO2 emissions reduction.

This report describes the system diagram and control algorithm of a prototype air-source cold climate heat pump (CCHP) using tandem vapor injection (VI) compressors. The prototype was installed in Fairbanks, Alaska and underwent field testing starting in 09/2016. The field testing results of the past six months, including compressor run time fractions, measured COPs and heating capacities, etc., are presented as a function of the ambient temperature. Two lessons learned are also reported.

For this study, we authored a new air source integrated heat pump (AS-IHP) model in EnergyPlus, and conducted building energy simulations to demonstrate greater than 50% average energy savings, in comparison to a baseline heat pump with electric water heater, over 10 US cities, based on the EnergyPlus quick-service restaurant template building. We also assessed water heating energy saving potentials using ASIHP versus gas heating, and pointed out climate zones where AS-IHPs are promising.

DOE has supported efforts for many years with the objective of getting a water heater that uses heat pump technology (aka a heat pump water heater or HPWH) successfully on the residential equipment market. The most recent previous effort (1999-2002) produced a product that performed very well in ORNL-led accelerated durability and field tests. The commercial partner for this effort, Enviromaster International (EMI), introduced the product to the market under the trade name Watter$aver in 2002 but ceased production in 2005 due to low sales. A combination of high sales price and lack of any significant infrastructure for service after the sale were the principal reasons for the failure of this effort. What was needed for market success was a commercial partner with the manufacturing and market distribution capability necessary to allow economies of scale to lead to a viable unit price together with a strong customer service infrastructure. General Electric certainly meets these requirements, and knowing of ORNL s expertise in this area, approached ORNL with the proposal to partner in a CRADA to produce a high efficiency electric water heater. A CRADA with GE was initiated early in Fiscal Year, 2008. GE initially named its product the Hybrid Electric Water Heater (HEWH).

The field study is planned to continue through the 2016 cooling season with the draft final project report due by September 30, 2016. This report provides a description of both installations and preliminary 2015 cooling and fall season performance results for the Knoxville site. For the August 18 through December 14 period, the Knoxville site GS-IHP provided 53.6% total source energy savings compared to a baseline electric RTU/heat pump and electric WH. Peak demand savings ranged from 33% to 59% per month. Energy cost savings of 53.1% have been achieved to date with more than half of that coming from reduced demand charges. Data on installation and maintenance costs are being collected and will be combined with total test period energy savings data for a payback analysis to be included in the project final report. The GS-IHP also saved a significant amount of carbon emissions. The total emission savings for the Knoxville site for the August-December 2015 period were ~0.8 metric tons. If trading for carbon credits ever becomes a reality, additional cost savings would be realized.

Reducing energy consumption in buildings is key to reducing or limiting the negative environmental impacts from the building sector. According to the United States (U.S.) Energy Information Administration (EIA), in 2013, commercial buildings consumed 18.1 quads of primary energy, which was 18.6% of the total U.S. primary energy consumption. The primary energy consumption in the commercial sector is projected to increase by 2.8 quads from 2013 to 2040, the second largest increase after the industrial sector. Further space heating, space cooling, and ventilation (HVAC) services accounted for 31% of the energy consumption in commercial buildings. The technical objective of this project is to demonstrate the capability of the new GS-IHP system to reduce overall energy use for space heating, space cooling, and water heating by at least 45% vs. a conventional electric RTU and electric WH in a light commercial building application. This project supports the DOE-Building Technologies Office (BTO) goals of reducing HVAC energy use by 20% and water heating by 60% by 2030.

In cold climate zones, e.g. ASHRAE climate regions IV and V, conventional electric air-source heat pumps (ASHP) do not work well, due to high compressor discharge temperatures, large pressure ratios and inadequate heating capacities at low ambient temperatures. Consequently, significant use of auxiliary strip heating is required to meet the building heating load. We introduce innovative ASHP technologies as part of continuing efforts to eliminate auxiliary strip heat use and maximize heating COP with acceptable cost-effectiveness and reliability. These innovative ASHP were developed using tandem compressors, which are capable of augmenting heating capacity at low temperatures and maintain superior part-load operation efficiency at moderate temperatures. Two options of tandem compressors were studied; the first employs two identical, single-speed compressors, and the second employs two identical, vapor-injection compressors. The investigations were based on system modeling and laboratory evaluation. Both designs have successfully met the performance criteria. Laboratory evaluation showed that the tandem, single-speed compressor ASHP system is able to achieve heating COP = 4.2 at 47 degrees F (8.3 degrees C), COP = 2.9 at 17 degrees F (-8.3 degrees C), and 76% rated capacity and COP = 1.9 at -13 degrees F (-25 degrees C). This yields a HSPF = 11.0 (per AHRI 210/240). The tandem, vapor-injection ASHP is able to reach heating COP = 4.4 at 47 degrees F (8.3 degrees C), COP = 3.1 at 17 degrees F (-8.3 degrees C), and 88% rated capacity and COP = 2.0 at -13 degrees F (-25 degrees C). This yields a HSPF = 12.0. The system modeling and further laboratory evaluation are presented in the paper.

This twelve-month field study analyzes the performance of a 7.56W (2.16-ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m(2) house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4 degrees C and 21.7 degrees C, respectively. The WA-GSHP shared the same 94.5 m vertical bore ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work, are identified using Exergy and energy analysis.Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources. (C) 2015 Elsevier Ltd. All rights reserved.

Evidence is provided to support the view that 68%-76% of the energy required to produce domestic hot water may be extracted from the ground which serves as a renewable energy resource. The case refers to a 345 m(2) research house located in Oak Ridge, Tennessee, 36.01 degrees N 84.26 degrees W in a mixed-humid climate with HOD of 2218 degrees C-days (3993 F-days) and CDD of 723 degrees C-days (1301 F-days). The house is operated under simulated occupancy conditions in which the hot water use protocol is based on the Building America Research Benchmark Definition which captures the water consumption lifestyles of the average family in the United States. The 5.3 kW (1.5-ton) water-to-water ground source heat pump (WW-GSHP) shared the same vertical bore with a separate 7.56 KW water-to-air ground source heat pump for space conditioning the same house. Energy and exergy analysis of data collected continuously over a twelve month period provide performance metrics and sources of inherent systemic inefficiencies. Data and analyses are vital to better understand how WW-GSHPs may be further improved to enable the ground to be used as a practical renewable energy resource. (C) 2015 Elsevier Ltd. All rights reserved.

A residential air-source integrated heat pump (AS-IHP) is under development in partnership with a U.S. manufacturer. A nominal 10.6 kW (3-ton) cooling capacity variable-speed unit, the system provides both space conditioning and water heating. This multi-functional unit can provide domestic water heating (DWH) in either full condensing (FC) (dedicated water heating or simultaneous space cooling and water heating) or desuperheating (DS) operation modes. Laboratory test data were used to calibrate a vapor-compression simulation model for each mode of operation. The model was used to optimize the internal control options for efficiency while maintaining acceptable comfort conditions and refrigerant-side pressures and temperatures within allowable operating envelopes. Annual simulations were performed with the AS-IHP installed in a well-insulated house in five U.S. climate zones. The AS-IHP is predicted to use 45 to 60% less energy than a DOE minimum efficiency baseline system while meeting total annual space conditioning and water heating loads. Water heating energy use is lowered by 60 to 75% in cold to warmer climates, respectively. Plans are to field test the unit in Knoxville, TN.