Search

Current research focus is migrating toward low-global-warming-potential (GWP) and natural refrigerants to address the human impact on climate change. In this paper, we examine 13 refrigerants from the perspective of the characteristic shape of their respective temperature–entropy (T–S) and the logarithm of the pressure versus inverse absolute temperature (log P vs. T–1) saturated phase boundary. Such analyses explain why certain refrigerants possess a re-entrant characteristic while others do not. The re-entrant region is due to skewness of the saturation boundary. The cause of skewness is investigated for its importance in heat pump performance, design, and configuration. Re-entrant behavior contributes to premature mechanical wear of compressor components. Knowledge of the properties of the phase boundary on either side of the critical point, is useful for a better perspective on discriminating refrigerants, as hydrochlorofluorocarbons are phased out and replacement refrigerants must be found. We conclude by identifying a candidate low-GWP refrigerant for heat pumps. In Part II, we evaluate all 13 refrigerants in thermodynamic cycles based on exergy analysis to identify sources of irreversibility, the root cause of systemic inefficiency.

Natural gas-driven absorption heat pumps (AHPs) are under renewed scrutiny as a viable technology for space conditioning and water heating for residential and commercial applications because of natural gas production trends, pricing, and the speculation that it might be a “bridge fuel” in the global transition toward energy sustainability. Since any level of natural gas combustion contributes to atmospheric carbon dioxide accumulation, the merits of natural gas–consuming absorption technology are reexamined in this paper from the point of view of expected efficiency as a driver for AHPs throughout the United States using a time-weighted bin temperature analysis. Such analyses are necessary because equipment standards for rated performance are restricted to one set ambient condition; whereas in actual practice, the AHP must perform over a considerably wider range of external conditions in which its efficiency may be vastly different from that at the rated condition. Quantification of variations in efficiency and system performance is imperative to address how to provide the desired application with the least environmental impact. In this paper, we examine limiting features in AHPs and relate them to systemic performances in 16 cities across all 8 climate zones in the United States, each containing 15 bin temperatures. The results indicate that the true expectation for AHP performance is significantly less than what might be optimized for the rated condition. Statistical measures of the variation in water heating COPs show that for most cities, the COP at the rated conditions is outside the 95% Confidence Interval. It is concluded that deployment of AHP water heaters may be restricted geographically by outdoor temperature constraints.

Heat pumps are currently being developed to reduce the energy footprint for residential and commercial building space conditioning and water heating loads in cold climates. To mitigate the nocuous impact of greenhouse gas emissions on the environment, and to create a carbon-neutral building stock, alternate lower-GWP refrigerants must also replace the predominant use of R-410A, without re-engineering the mechanical hardware. In this paper, we analyze the performance of lower-GWP alternative refrigerants (R-32, R-452B, R-454B, and R-466A) relative to the conventional R-410A and draw conclusions on the relative performances to meet cooling loads. The simulations are accomplished using the heat pump design model, a well-known, public-domain design tool with a free web interface and downloadable desktop version to support public use and the HVAC R&amp, D community. The contributions contain detailed, hardware-based heat exchanger and system analyses to provide a comprehensive assessment. The results of the simulation are scrutinized from the first (capacity and energy efficiency) and second laws (exergy analysis) to identify sources of systemic inefficiency, the root cause of lost work. This rigorous approach provides an exhaustive analysis of alternate lower-GWP refrigerants to replace R-410A using the same hardware. The results have practical value in engineering heat pumps in an economy that is compelled to alter by the consequences and uncertainties of climate change, to reduce its anthropogenic carbon footprint.

The choice of driving a heat pump with an electrically- or a thermally-driven engine is a vexing question complicated by the carbon footprint and environmental impact of using electricity versus natural gas (or waste heat) as the main driver for the respective engines. Useful work generated by these two distinct engines is the focal point of this paper, addressing a key question: which engine presents a better choice for a given heat pumping application within the constraints of energy and environmental stewardship? We examine this question comprehensively through the methodology of energy, exergy, and availability analysis, explaining clearly, why the output of work from these two distinct engines is inherently vastly different. Thermodynamic consistency is guaranteed by satisfaction of the First and Second Laws applied to closed systems and their subsystems. The general conclusion is that thermally-driven engines are not industrious converters of heat to mechanical work, for heat pumps.

The objective of this work is to simulate a single effect (SE) ammonia-water heat pump for domestic water heating, with innovative aspects for cycle simulation and eventual practical implementation. The following practical difficulties are addressed in the simulation: 1. seasonal temperature variations change the operating conditions of the distillation column, calling for insightful design to maintain a suitable refrigerant concentration in all seasons, and particularly in winter; 2. The evaporator activated by outdoor air suffers from immoderate heat transfer requirements, and these demands are considerably reduced if the activation is done by products of combustion; 3. Pumps have head requirements that can be assuaged by judicious selection and inlet solution subcooling. The variables that need to be controlled if the same column is to be used all year round are specified. As configured with the innovations mentioned, the cycle simulation yields a coefficient of performance within the expected range for a single effect, but it harbors the promise of a much smaller evaporator, of small overall height, and of a distillation column capable of operating effectively all year round with the same feed point.

Condenser evaporative pre-coolers provide a low cost retrofit option for existing packaged rooftop air conditioning application units. This paper aimed to provide a comprehensive study to assess energy savings and peak power reductions of condenser evaporative cooling. Condenser evaporative cooling leads to a lower temperature of the air entering the condenser of a rooftop unit, which results in smaller compressor power consumption. Using EnergyPlus building energy simulations, we mapped the impacts on energy savings and energy reductions at peak ambient temperatures in three building types and 16 locations with levels of pad effectiveness and demonstrated the effects on air conditioner using either R22 or R410A as refrigerants. Economics and control strategy to maximize the cost saving were also investigated. The results demonstrate that energy savings are much greater for HVAC systems with the refrigerant R410A than they are with R22, and evaporative pre-cooling provides the opportunity for annual energy savings and peak demand reductions, with significant potential in hot, dry climates. Additionally, we validated an improved mathematical model for estimating the condenser pre-cooling wet bulb efficiency which shows clear advantage over the current EnergyPlus model.

This paper demonstrates a new method by which the energy storage density of compressed air systems is increased by 56.8% by changing the composition of the compressed gas to include a condensable component. A higher storage density of 7.33 MJ/m3 is possible using a mixture of 88% CO2 and 12% N2 compared to 4.67 MJ/m3 using pure N2. This ratio of gases representing an optimum mixture was determined through computer simulations that considered a variety of different proportions from pure CO2 to pure N2. The computer simulations are based on a thermodynamic equilibrium model that predicts the mixture composition as a function of volume and pressure under progressive compression to ultimately identify the optimal mixture composition (88% CO2 + 12% N2). The model and simulations predict that the optimal gas mixture attains a higher energy storage density than using either of the pure gases.

This rebuttal in the form of a letter to the Editor is prepared by the corresponding author of the paper, “Variability of absorption heat pump efficiency for domestic water heating and space heating based on time-weighted bin analysis, Applied Thermal Engineering, Volume 130, 5 February 2018, 515–527. https://orproxy.lib.utk.edu:2113/10.1016/j.applthermaleng.2017.10.142” in response to the “concerns“ sent to the Editor by Dr. Chris Keinath and Mr. Michael Garrabrant of Stone Mountain Technologies, Inc., (SMTI) Johnson City, TN.

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°N 84.26°W in a mixed-humid climate with HDD of 2218 °C-days (3993 °F-days) and CDD of 723 °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.

This twelve-month field study analyzes the performance of a 7.56 W (2.16-ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m2 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 kW h at summer and winter thermostat set points of 24.4 °C and 21.7 °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.

In this paper, a techno-economic model / cost reduction analysis of a low-cost, dispatchable / scalable, efficient Ground-Level Integrated Diverse Energy Storage (GLIDES) system is analyzed, along with a review of existing state-of-the-art energy storage technologies. The introduced technology, GLIDES, which was invented at the Oak Ridge National Laboratory (ORNL), stores energy by compression and expansion of air using water as a liquid piston inside high-pressure reservoirs. GLIDES is introduced by combining Pumped Hydroelectric Storage (PHS) and Compressed Air Energy Storage (CAES) technologies. By replacing inefficient gas compressor and turbine with higher efficiency liquid turbomachines for liquid-piston compression/expansion, GLIDES achieves higher roundtrip efficiency than other gas compression-based energy storage technologies and is a scalable energy storage system. For cost reduction purposes, various pressure reservoirs including steel vessels, carbon fiber vessels, pipe segments, and underground pressure reservoirs are analyzed in this paper. Based on the analyzed data using the models discussed in this paper, energy storage costs as low as ∼$14/kWh and ∼$346/kWh (roundtrip efficiency (RTE) ∼80%) can be achieved for a grid-scale GLIDES using depleted oil/gas reservoirs and high-pressure pipe segments respectively.

This paper presents analysis of a 5.275 kW (1.5-ton) water-to-water ground source heat pump (WW-GSHP) satisfying hot water needs in a 345 m 2 research house operated under simulated occupancy conditions. The hot water use protocol from the Building America Research Benchmark Definition claims to capture the living habits of the average American household and its impact on energy consumption. Energy and exergy analyses provide insight on system efficiency and sources of irreversibility, the main cause of wasted energy. The WW-GSHP shared the ground loop with a 7.56 kW water to air ground source heat pump (WA-GSHP) to space condition the same house. Understanding the performance of GSHPs is vital if the ground is to be used as a viable renewable energy resource.

This paper presents data, analyses, measures of performance, and conclusions for a ground-source heat pump (GSHP) providing space conditioning to a 345 m 2 house whose envelope is made of structural insulated panels. The entire house thermal load with R SI -3.7 (R US -21) walls, triple-pane windows (U-factor of 1.64 W m −2 K (0.29 Btu h −1 ft −2 °F −1 )) and solar heat gain coefficient of 0.25, a roof assembly with overall thermal resistance of about R SI -8.8 (R US -50), and low leakage rates of 0.74 ACH at 50 Pa, was satisfied with a 2.16 ton (7.56 kW) GSHP unit. Coefficient of performance is calculated on the basis of the total power input (including duct, ground loop, and control power losses). Exergy analysis provides a true measure of how closely actual performance approaches the ideal, and it unequivocally identifies, better than energy analysis does, the sources and causes of lost work — the root cause of system inefficiencies and wasted energy.

In their landmark paper published in 1948, Stokes and Robinson (J. Am. Chem. Soc. 1948, 70, 1870−1878) proposed a modified form of the Brunauer−Emmett−Teller (BET) adsorption isotherm to explain the water activity of various concentrated 1:1 and 2:1 aqueous electrolytes. Their pioneering idea of viewing such solutions as an irregular ionic lattice structure inspired much of the author’s work from the mid 1980s to the present time. This paper, written in celebration of Prof. Stokes’ 90th birthday anniversary, briefly describes the author’s contribution toward further development of the theory, its capabilities, and future directions.

The statistical mechanical description of multilayer adsorption culminating in the Brunauer–Emmet–Teller (BET) adsorption isotherm for aqueous electrolytes as developed by Ally and Braunstein [M.R. Ally and J. Braunstein, Fluid Phase Equilibria. 87 (2) (1993) 213–236] is used to predict the liquidus behavior of CaCl2·H2O across the entire composition range (from the melting point of pure water to the melting point of anhydrous calcium chloride), including possible metastable crystalline phases. The method requires as input the two BET parameters r, the statistically averaged number of adsorption sites and ɛ, the energy of adsorption of water in excess of the energy of condensation of pure water. Usually it suffices to keep r and ɛ constant, typically evaluated at 298.15 K, but in the case of CaCl2·H2O, it is found that both r and ɛ must be considered temperature dependent in order to predict the liquidus curve, eutectic and peritectic points with reasonable accuracy over the large temperature and compositional range for this binary system. The theory and methodology in this paper enables detailed predictions of liquidus curves over much wider temperature and composition ranges than that reported by an alternate method [D. Zeng, H. Zhou,W. Voigt, Fluid Phase Equilibria 253 (2007) 1–11].

Between August 2011 and September 2015, Oak Ridge National Laboratory (ORNL) and Nordyne, LLC (now Nortek Global HVAC LLC, NGHVAC) engaged in a Cooperative Research and Development Agreement (CRADA) to develop an air-source integrated heat pump (AS-IHP) system for the US residential market. Two generations of laboratory prototype systems were designed, fabricated, and lab-tested during 2011-2013. Performance maps for the system were developed using the latest research version of the DOE/ORNL Heat Pump Design Model, or HPDM, (Rice 1991; Rice and Jackson 2005; Shen et al 2012) as calibrated against the lab test data. These maps were the input to the TRNSYS (SOLAR Energy Laboratory, et al, 2010) system to predict annual performance relative to a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of 13 SEER air-source heat pump (ASHP) and resistance water heater with Energy Factor (EF) of 0.9). Predicted total annual energy savings, while providing space conditioning and water heating for a tight, well insulated 2600 ft2 (242 m2) house at 5 U.S. locations, ranged from 46 to 61%, averaging 52%, relative to the baseline system (lowest savings at the cold-climate Chicago location). Predicted energy use for water heating was reduced 62more » to 76% relative to resistance WH. Based on these lab prototype test and analyses results a field test prototype was designed and fabricated by NGHVAC. The unit was installed in a 2400 ft2 (223 m2) research house in Knoxville, TN and field tested from May 2014 to April 2015. Based on the demonstrated field performance of the AS-IHP prototype and estimated performance of a baseline system operating under the same loads and weather conditions, it was estimated that the prototype would achieve ~40% energy savings relative to the minimum efficiency suite. The estimated WH savings were >60% and SC mode savings were >50%. But estimated SH savings were only about 20%. It is believed that had the test house been better insulated (more like the house used for the savings predictions noted above) and the IHP system nominal capacity been a bit lower that the energy savings estimate would have been closer to 45% or more (similar to the analytical prediction for the cold climate location of Chicago).« less

The irregular ionic lattice model (IILM) is applied to predict the vapor pressures and solubilities of carbon dioxide dissolved in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and in 1-n-octyl-3-methylimidazolium tetrafluoroborate ([C8mim][BF4]) ionic liquids at temperatures ranging from 298.15 to 333.15 K. The model contains only two parameters; they are shown to be independent of an arbitrarily chosen reference state. The parameters show a slight dependence on temperature, but this dependence is ignored in computations to demonstrate the rigor of the IILM in predicting CO2 solubility at high and low pressures at various temperatures. Model predictions are compared against the experimental data of Anthony et al. (J. Phys. Chem. B 2002, 106, 7315) and of Blanchard et al. (J. Phys. Chem. B 2001, 105, 2437). The usefulness of the model is in predicting CO2 solubilities at temperatures and pressures where experimental data are unavailable.

The theory of multilayer adsorption for concentrated aqueous electrolytes developed by Ally and Braunstein (1998) is used to calculate the thermodynamic activities and osmotic coefficients of supersaturated solutions of (NH4)2SO4(aq) and NaCl (aq) which are among man-made aerosols of atmospheric importance. The basis of the model is the postulate of Stokes and Robinson that concentrated aqueous electrolytes may be viewed as an irregular ionic lattice structure. Application to the electrolytes mentioned above is a special case of the generalized results which are proven (Ally and Braunstein, Braunstein and Ally) to be consistent with the Gibbs–Duhem equation. Calculated thermodynamic properties are compared against experimental data from isopiestic and electrodynamic balance (EDB) measurements.

The Stokes-Robinson modification of the Brunauer-Emmett-Teller (BET) adsorption isotherm is used to calculate the liquidus curve of NaNO3(aq) including the eutectic point and metastable phases. The method described here represents a simplified approach to predict the liquidus curves with sparse information.

The values of the two Brunauer−Emmett−Teller (BET) parameters calculated by Stokes and Robinson (1948) are reevaluated using recent experimental data on the activity coefficients of CaCl2(aq) reported by Rard and Clegg (1997). At the 95% confidence level, no significant statistical differences are observed in the values of the BET parameters reported in this work and those reported by Stokes and Robinson (1948). The water activities aw, osmotic coefficients φ, and mean ionic activity coefficients, γ± of CaCl2(aq) are then calculated from saturation to dilute solution. Since the standard state of the solute in the BET model is the anhydrous liquid electrolyte rather than the infinitely dilute solution, the technique of Ally and Braunstein (1996) is utilized to obtain the mean ionic activity coefficients of CaCl2(aq) over the entire concentration range. The differences between the chemical potentials of the solute in the infinitely dilute solution standard state (hypothetical) and the anhydrous liquid elect...

Approximately 33 years after Stokes and Robinson's modification of the Brunauer– Emmett–Teller (BET) adsorption isotherm paved the way for experimental investigations of the water activities and properties of concentrated aqueous electrolytes, Abraham derived an equation giving the activity of a salt on the basis of the same model, but restricted his result to a binary aqueous system consisting of one salt only. Many investigators have used Stokes and Robinson's modification to show good agreement between experimental and calculated water activities even for ternary and quaternary aqueous solutions, if the system is treated as a pseudobinary. However, no previous (theoretical) attempt has been made to go beyond the single salt or pseudobinary restriction of Abraham. In this paper, we categorically prove that there is no fundamental limitation that restricts the BET model to a single electrolyte. We verify the consistency of our results through satisfaction of the Gibbs–Duhem relationships and by showing agreement between the calculated and experimental data of Iyoki on water vapor pressures for {x(2.8LiCl + LiNO3)+(1−x)H2O}, wherex=ωMw/{ωMw+ (1−ω)Ms}; ω denotes the mass fraction of lithium salts; andMwandMsdenote the molar masses of H2O and of (2.8LiCl + LiNO3), respectively. In predicting activities of the components of {x(2.8LiCl + LiNO3)+(1−x)H2O}, no experimental data on this ternary system are utilized. This fact underlies the predictive quality of the theoretical model presented in our paper. By induction, we extend our results to the case of (water + N electrolytes).

A one-dimensional electrokinetic model has been developed to simulate the transport of cesium and strontium ions through a concrete disk. The model predicts the variation of the ion concentrations in the anolyte and catholyte. The sensitivity of the ion concentration in the anolyte and catholyte to the overall mass transfer coefficient and ion diffusion coefficient is investigated. Using reasonable values for the diffusion coefficient and the overall mass transfer coefficient, good agreement is obtained between the experimental and computed variations in the anolyte concentrations. The results for the catholyte concentrations are in qualitative agreement with the experimental observations. The variation in the pH in the anolyte and catholyte, and the voltage drop across the disk, are predicted by the model.

The decontamination of concrete is a major concern in many Department of Energy (DOE) facilities. Numerous techniques (abrasive methods, manual methods, ultrasonics, concrete surface layer removal, chemical extraction methods, etc.) have been used to remove radioactive contamination from the surface of concrete. Recently, processes that are based on electrokinetic phenomena have been developed to decontaminate concrete. Electrokinetic decontamination has been shown to remove from 70 to over 90% of the surface radioactivity. To evaluate and improve the electrokinetic processes, a model has been developed to simulate the transport of ionic radionuclei constituents through the pores of concrete and into the anolyte and catholyte. The model takes into account the adsorption and desorption kinetics of the radionuclei from the pore walls, and ion transport by electro-osmosis, electromigration, and diffusion. A numerical technique, orthogonal collocation, is used to simultaneously solve the governing co...

Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of conceret. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of cesium than strontium, while some positive results were obtained for the transport of cobalt through concrete using EDTA and for uranium using carbonate. *Managed by Lockheed Martin Energy Research Corp. for the U. S. Department of Energy under contract DE-AC05-96OR22464.

Between October 2008 and May 2013 ORNL and ClimateMaster, Inc. (CM) engaged in a Cooperative Research and Development Agreement (CRADA) to develop a groundsource integrated heat pump (GS-IHP) system for the US residential market. A initial prototype was designed and fabricated, lab-tested, and modeled in TRNSYS (SOLAR Energy Laboratory, et al, 2010) to predict annual performance relative to 1) a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of air-source heat pump (ASHP) and resistance water heater) and 2) a state-of-the-art (SOA) two-capacity ground-source heat pump with desuperheater water heater (WH) option (GSHPwDS). Predicted total annual energy savings, while providing space conditioning and water heating for a 2600 ft{sup 2} (242 m{sup 2}) house at 5 U.S. locations, ranged from 52 to 59%, averaging 55%, relative to the minimum efficiency suite. Predicted energy use for water heating was reduced 68 to 78% relative to resistance WH. Predicted total annual savings for the GSHPwDS relative to the same baseline averaged 22.6% with water heating energy use reduced by 10 to 30% from desuperheater contributions. The 1st generation (or alpha) prototype design for the GS-IHP was finalized in 2010 and field test samples were fabricated for testing by CM and by ORNL. Two of the alpha units were installed in 3700 ft{sup 2} (345 m{sup 2}) houses at the ZEBRAlliance site in Oak Ridge and field tested during 2011. Based on the steady-state performance demonstrated by the GS-IHPs it was projected that it would achieve >52% energy savings relative to the minimum efficiency suite at this specific site. A number of operational issues with the alpha units were identified indicating design changes needed to the system before market introduction could be accomplished. These were communicated to CM throughout the field test period. Based on the alpha unit test results and the diagnostic information coming from the field test experience, CM developed a 2nd generation (or beta) prototype in 2012. Field test verification units were fabricated and installed at the ZEBRAlliance site in Oak Ridge in May 2012 and at several sites near CM headquarters in Oklahoma. Field testing of the units continued through February 2013. Annual performance analyses of the beta unit (prototype 2) with vertical well ground heat exchangers (GHX) in 5 U.S. locations predict annual energy savings of 57% to 61%, averaging 59% relative to the minimum efficiency suite and 38% to 56%, averaging 46% relative to the SOA GSHPwDS. Based on the steady-state performance demonstrated by the test units it was projected that the 2nd generation units would achieve ~58% energy savings relative to the minimum efficiency suite at the Zebra Alliance site with horizontal GHX. A new product based on the beta unit design was announced by CM in 2012 – the Trilogy 40® Q-mode™ (http://cmdealernet.com/trilogy_40.html). The unit was formally introduced in a March 2012 press release (see Appendix A) and was available for order beginning in December 2012.

Electrolyte mean ionic activity coefficients, γ±, are calculated from the Stokes-Robinson application of the Brunauer-Emmett-Teller (BET) adsorption model for seven electrolytes (NaOH, HCl, KOH, CaCl2, LiCl, LiBr and Ca(NO2)3). Only two model parameters are needed, which are derived from water vapor pressure measurements. Results were compared with experimental mean ionic activity coefficients (γ±). Because the standard state for the BET model is the anhydrous electrolyte rather than the infinitely dilute solution, it is necessary to adjust for the differing standard states by comparing the BET and experimental γ± values at one ‘anchoring’ concentration. The higher this ‘anchoring’ concentration, the better is the agreement between the BET and experimental mean ionic activity coefficients over the entire concentration (molality, mol kg−1) range except at the two extremes of nearly pure water and nearly pure electrolyte. This is because the BET model lacks a finite limit at infinite dilution, and the experimental data are referenced to the infinite dilute solution. The BET model is well-behaved and in good agreement with experimental data on γ±.

Evaporative condenser pre-cooling expands the availability of energy saving, cost-effective technology options (market engagement) and serves to expedite the range of options in upcoming codes and equipment standards (impacting regulation). Commercially available evaporative pre-coolers provide a low cost retrofit for existing packaged rooftop units, commercial unitary split systems, and air cooled chillers. We map the impact of energy savings and peak energy reduction in the 3 building types (medium office, secondary school, and supermarket) in 16 locations for three building types with four pad effectivenesses and show the effect for HVAC systems using either refrigerants R22 or R410A

Ally, M.R. and Braunstein, J., 1993. BET model for calculating activities of salts and water, molar enthalpies, molar volumes and liquid-solid phase behavior in concentrated electrolyte solutions. Fluid Phase Equilibria , 87: 213-236. This paper demonstrates the calculation of the activities of salts and water, excess properties and solid phase equilibria in aqueous media by applying the general properties of solutions to extensions of the Stokes-Robinson application of the Brunauer-Emmett-Teller (BET) adsorption isotherm. Such a comprehensive treatment provides a thermodynamically consistent method of obtaining equilibrium properties of moderately to highly concentrated (up to molten salt regime) aqueous solutions with as few as two parameters, plus a third parameter in the case of molar volumes. The present state of development allows treatment of electrolytes with common anions or common cations, but does not yet include reciprocal salt mixtures. Multicomponent aqueous solutions can be treated as pseudobinary if desired, by invoking the proposed mixing rules. The real advantage of the method lies in the use of a minimal number of parameters to represent a wide variety of thermodynamic properties with reasonable accuracy over relatively wide temperature and concentration ranges. This comprehensive treatment is verified through comparison of predicted results and experimental data on: water vapor pressure-temperature-composition behavior of aqueous LiBr and of (Li, K, Na)NO 3 mixtures; partial excess and molar volume-temperature-composition of aqueous LiBr and of (Li, K, Na)NO 3 mixtures; partial excess and integral molar enthalpy-temperature-composition of aqueous LiBr; phase equilibria of NaOH in aqueous solution.

This paper reports that the refractive indexes of water-lithium bromide solutions were measured in the temperature range from 5.0 to 80.0 {degrees}C and in the range of salt concentrations from 0.00 (deionized water) to 58.90 mass %. An electrolyte solution of LlBr in water was chosen for study because of its wide use as an absorption chiller fluid. The concentration of LlBr aqueous solution was determined by argentimetric titration using tetrabromofluoresceln (Eosin) as an adsorption indicator and was checked at a few discrete concentrations (10.06, 20.30, and 58.90 mass % LlBr) against the values obtained by gravimetric analysis. The deviation between values obtained using these two techniques was found to be less than 0.27 mass %. The refractive indexes are shown to represent a reliable and convenient way of measuring the concentration of salt (or water) in LlBr solutions with accuracies of {plus minus}0.3 mass % salt.

This report assesses the use of air conditioning load for providing spinning reserve and discusses the barriers and opportunities. Air conditioning load is well suited for this service because it often increases during heavy load periods and can be curtailed for short periods with little impact to the customer. The report also provides an appendix describing the ambient temperature effect on air conditioning load.

This paper describes experimental procedures and techniques for measuring densities and/or refractive indexes of aqueous salt solutions between 25 and 200 [degrees]C and with 18.90-90.50 wt % mixed salt (LINO[sub 3], KNO[sub 3], and NaNO[sub 3]). An electrolyte solution of (LI, K, Na) NO[sub 3] slats in water was chosen for study because of its recent development as a potential high-temperature heat pump fluid, but any other appropriate fluid may be accommodated for study in the apparatus. The densities and refractive indexes are shown to represent a convenient way to measuring the concentration of salt (or water), and accuracies of [plus minus]0.8 and [plus minus]0.3 wt % total mixed salt were achieved by using the above two methods, respectively.

The goals and objectives of the technical task plan (TTP) are to (1) describe the nature and extent of concrete contamination within the Department of Energy (DOE) complex and emerging and commercial technologies applicable to these problems; (2) to match technologies to the concrete problems and recommend up to four demonstrations; (3) to initiate recommended demonstrations; and (4) to continue investigation and evaluation of the application of electrokinetic decontamination processes to concrete. This document presents findings of experimental and theoretical studies of the electrokinetic decontamination (EK) process and their implications for field demonstrations. This effort is an extension of the work performed under TTP 142005, ``Electroosmotic Concrete Decontamination. The goals of this task were to determine the applicability of EK for treating contaminated concrete and, if warranted, to evaluate EK as a potential technology for demonstration. 62 refs.

A procedure for the prediction of wall-bed heat transfer coefficient for bubble columns and gas-solid fluidized beds is developed on the basis of hydrodynamic behavior of these contactors. A comparison between the predicted and experimental values of heat transfer coefficient over a wide range of design and operating variables is presented. An attempt is made to analyze the occurrence of maxima in heat transfer coefficient with respect to gas velocity in the case of fluidized beds. A procedure for the calculation of the optimum superficial gas velocity is outlined.

Les resultats experimentaux obtenus avec du cuivre, du verre et du Plexiglas, montrent que la perte de charge due aux contributions electrostatiques sont fonction a la fois de la densite du nombre des particules et de la capacite de charge maximale des particules