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Shen, Bo

Publications and source records attributed to Shen, Bo.

At least 127 records · Page 7
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DOE OSTI2018

Extending ORNL HPDM capabilities for design and optimization of new refrigerant blends - FY18 3rd quarterly milestone: a trial version published online for modeling and design ac units using low GWP refrigerants

Based on exhaustive literature survey, we updated the DOE/ORNL HPDM to include most up-to-date heat transfer and pressure drop correlations suitable for modelling low GWP HFO blends and built up a comprehensive refrigerant property database including all the emerged HFO refrigerants. The upgraded HPDM has been released online, containing a desktop version for free download. The new release includes five system examples of room and commercial air conditioner (AC) units, which facilitates modelling and designing AC units using low GWP refrigerants. Geometry and configurations of the units were obtained from ORNL’s low-GWP refrigerant drop-in investigations [1] [2]. The published models have been calibrated to match the measured data. The new public-domain, free-to-use tool will help the US industry design their AC units using the new refrigerants and shorten the learning curve.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

ECC Refrigerator: Characterize Performance of a Prototype Electrochemical Compressor

This report documents experimental study to characterize performance of a prototype electrochemical compressor, provided by Xergy INC. It describes the working mechanism and its electrochemical efficiency and isentropic compression efficiency. The experimental results demonstrate that the prototype compressor is able to pump hydrogen flow from 25 psia to 140 psia, and deliver the flow rate as predicted. On the other hand, its efficiency level is low, having the electrochemical efficiency less than 40%, and isentropic efficiency below 47%. Using two identical ECC compressors in parallel will reduce the current density and ohm loss, which can increase the isentropic efficiency up to 67% with increased cost. Further improvements on the compressor are suggested, e.g. using more conductive membrane, etc.

42 ENGINEERING↗
DOE OSTI2018

Experimental Study to Characterize Performance of a Prototype Electrochemical Compressor

This paper reports experimental study to characterize performance of a prototype electrochemical hydrogen compressor, provided by Xergy INC. It describes the working mechanism and reports its measured electrochemical efficiency and isentropic compression efficiency. The experimental results demonstrate that the prototype compressor can pump hydrogen flow from 25 psia to 140 psia and deliver the flow rate as theory. The electrochemical efficiency was measured around 40%, and isentropic efficiency around 47%. Using two identical ECC compressors in parallel will reduce the current density and ohm loss, which can increase the isentropic efficiency to 67% with increased cost. Further improvements on the compressor are suggested, e.g. using more conductive membrane, etc.

Shen, Bo↗
DOE OSTI2018

Model-Based Air Flow Path Optimization of Heat Pump Clothes Dryer

A heat pump clothes dryer (HPCD) uses a vapor compression system to dry clothes. The condenser heats air, which passes through the drum to evaporate moisture out of the clothes, and the evaporator condenses water out of the air stream. As a result, the HPCD can achieve 50% energy savings compared to a conventional electric resistance dryer. In this work we developed a physics-based, quasi-steady-state HPCD system model with detailed heat exchanger and compressor models. The system model can simulate the inherently transient HPCD drying process, to size components, and to reveal trends in key variables (e.g. compressor discharge temperature, power consumption, required drying time, etc.) The system model was calibrated using experimental data from a prototype HPCD. Air leakages, in and out, along the closed air circulation path of HPCD cause varied effects on the performance. Understanding the location, magnitude, and direction of air leakage of the heat pump clothes dryer is critical for accurately characterizing the performance and developing a high-performance design. The system model was used to reveal the impacts. In addition, model-based parametric optimizations were conducted to design the HPCD charge inventory, flow rate, air path and leak points for optimum performance.

Shen, Bo↗
DOE OSTI2018

Experimental Measurements of Clothes Dryer Drum Heat and Mass Transfer Effectiveness

Accurate system modeling of a clothes dryer requires a drum component model that displays correct trends with respect to changing conditions. In this work, a model of drum heat and mass transfer effectiveness is adopted. Within this framework, experimental measurements of drum effectiveness are investigated with respect to several variables: drum volume, load mass, cloth type, drum volumetric air flow rate, and drum entering air temperature. These data can inform the modeling and simulation of any clothes dryer with horizontal-axis, axial-flow tumble-type clothes dryer drum.

Gluesenkamp, Kyle R.↗
DOE OSTI2018

A New Strategy to Synthesize Anisotropic SmCo 5 Nanomagnets

We report a simple strategy to synthesize anisotropic SmCo 5 nanoplates. The strategy involves the pre-synthesis of 125 x 12 nm Sm(OH) 3 nanorods and 10 nm Co nanoparticles followed by self-assembly of these nanorods and nanoparticles into Sm(OH) 3 -Co nanocomposites. Once embedded in CaO matrix, the nanocomposite is subject to high temperature (850 °C) annealing in the presence of Ca, leading to the formation of 125 x 10 nm SmCo 5 nanoplates, which are dispersible in ethanol, allowing the alignment in epoxy resin under a 20 kOe magnetic field. The aligned SmCo 5 nanoplates show a square hysteresis behavior with room temperature coercivity reaching 30.1 kOe, which is among the highest values ever reported for SmCo 5 made from chemical methods. The work provides a new approach to high-performance anisotropic SmCo 5 for permanent magnet applications.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

Low-GWP Refrigerant Evaluation in AC Systems for High Ambient Temperature Applications - Literature Survey for Impact of Varying Refrigerant Charge on AC System Performance

The report summarizes the findings of ASHRAE Research project 1173, by Purdue University to assess the impact of varying refrigerant charge on air conditioner (AC) system performance. This project tested six residential air conditioners with varying the system charge in a wide range, using TXV or fixed-orifice as the expansion device. In summary, the systems using fixed-orifices are much more sensitive to reduction of the system charge than using TXVs. The systems using fixed-orifices had noticeable performance degradations when reducing the system charge below 90% relative to the factory charge; the systems using TXVs experienced drastic performance penalties when decreasing the system charge below 80%. In the cases, the TXVs were all fully open and couldn’t control the target superheat degree. In order to limit the system charge for lower-GWP refrigerants, without degrading the system performance much, the AC systems are recommended to use TXV and compact heat exchangers, i.e. micro-channel heat exchangers.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Extending ORNL HPDM Capabilities for Design and Optimization of New Refrigerant Blends – FY18 1st Quarterly Milestone: Perform literature review to collect heat transfer, pressure drop correlations and compressor mapping method for alternative refrigerants

Through a comprehensive literature survey, we identified heat transfer and pressure drop correlations for two-phase evaporation and condensation in fin-and-tube coils using microfin tubes and micro-channel heat exchangers. We also developed a compressor mapping method to convert the maps originally developed for R-22 or R-410A to be used by the alternative lower GWP refrigerants. The correlations and method will be implemented in HPDM for design and optimization of air conditioners and heat pumps using the new refrigerants/blends.

42 ENGINEERING↗
DOE OSTI2017

The effects of MnO{sub 2} addition on the structure and dielectric properties of the strontium barium niobate glass-ceramics

Highlights: • A small amount of MnO{sub 2} doping the SBN-glass-ceramics makes BDS reach to 1470.6 kV/cm. • The theoretical energy storage density of the SBN-glass-ceramics with MnO{sub 2} addition gets 9.2 J/cm{sup 3}. • A small amount MnO{sub 2} doping the BSN-glass-ceramics makes the leakage current densities decrease to 10{sup −6} A/cm{sup 2}. • A small amount of MnO{sup 2} doping the SBN-glass-ceramics can effectively decrease the dielectric loss of the materials. - Abstract: The effects of MnO{sub 2} content on the structure and dielectric properties of the SBN-glass-ceramics were studied. The results show that a small amount of MnO{sub 2} doping of the SBN-glass-ceramics can make their microstructure become denser and more uniform and MnO{sub 2} doping of the SBN-glass-ceramics, as a grain growth inhibitor, has an evident effect on the reduction of grain sizes. The Mn ions exist in the form of Mn{sup 3+} and Mn{sup 4+} ions in the SBN-glass-ceramics, as confirmed by XPS measurements and Mn{sup 3+} and Mn{sup 4+} ions easily form charge defect complexes, which causes the leakage current densities of the SBN-glass-ceramics to obviously decrease. And a small amount of MnO{sub 2} doping of the SBN-glass-ceramics can effectively decrease the dielectric loss of the materials. When 0.05 mol% MnO{sub 2} is added to the SBN-glass-ceramics, the BDS is up to 1470.6 kV/cm and the theoretical energy storage density reaches the maximum value of 9.2 J/cm{sup 3}.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Characterization of Wrapped Coil Tank Water Heater during Charging/Discharging

Heat pump water heaters (HPWH) are an energy efficient method for water heating compared to conventional electric water heaters. A wrapped coil around the water tank is often used as the condenser for the heat pump for such applications. Thermal stratification, caused by varying heat transfer rate from the condenser to the water depending on the phase of the refrigerant and the wrap configuration, is often observed inside the tank, especially for HPWHs using CO2 as the refrigerant. The current study investigates the impact of the charging/discharging process on thermal stratification. A series of simulations were conducted based on the draw patterns recommended by the DOE method of test for rating water heater performance. We also analyzed the water circulation patterns during charging/discharging process. The thermal stratification was adversely affected because of the circulation even when the Heat Pump (HP) was operational. It was observed that a relatively higher charge/discharge flow rate disrupts the thermal stratification quickly and thus lowers the supply water temperature. Furthermore, the duration of charging/discharging also plays an important role. It was noticed that the back flow has insignificant effect on the supply water temperature if charging/discharging time is relatively small. However, the effect was obvious for larger water draw flow rates that last for longer time.

Elatar, Ahmed↗
DOE OSTI2017

ECC Refrigerator: Investigate Potential Energy Savings and Likelihood of Success if an ECC is Used Instead of a Typical Vapor Compressor

This report estimates energy saving potential of a refrigerator using an electrochemical compressor (ECC) and metal hydride heat exchangers, versus a baseline refrigerator using a single-speed reciprocating compressor. The ECC technology has is more efficient at high pressure ratio and has better part-load performance. In addition, metal hydrides are solid refrigerants suitable for extensive applications, having larger formation heat. It has the potential to achieve energy saving over 20% than the baseline refrigerator, after we break the technical barriers on the path. Based on evaluation of the project against the must meet criteria, it meets the requirements for a “go” decision.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗