Steady-state Testing Conditions Research Articles

Realistic operation of two residential cordwood-fired outdoor hydronic heater appliances—Part 1: Particulate and gaseous emissions

ABSTRACT This study investigated how heat demand and fuel loading affect the emissions from outdoor wood-fired hydronic heaters by testing two such appliances using an integrated-duty cycle test method. This test included transient operating conditions, such as cold and hot-starts and modulation between 15 and 100% of maximum rated output. Emission values indicate transient operating conditions produce higher emissions than steady state operation. Cold starts resulted in elevated particulate matter emission factors for both appliances; in one case the particulate matter emission factor for this period was >3500 mg/MJ, which represented emissions 20 times the average value. Additionally, when heat demand was cycled—elevated CO emission factors were measured, with values >5000 mg/MJ for both appliances and more than 3 times the appliance averages, respectively. It follows that the appliance average particulate matter emission factors and CO emission factors were not representative of the actual EF values during these transient periods. In contrast, methane emission factors were relatively stable throughout all tested combustion conditions; however, they were much higher than oil-fired appliances are therefore should not be ignored. These findings demonstrate that wood-fired hydronic heater emissions during transient operating conditions can be significantly greater than emissions during steady-state test conditions, such as those used in typical certification tests. Consequently, certification test values for particulate matter and CO emission factors may significantly underestimate the actual emissions of these appliances when operated in a home. Use of integrated duty-cycle test protocols that capture cold-starts and reloading are better for representing in-use operations of wood-fired hydronic heaters and provide more realistic emissions and delivered efficiency measurements. Implications: In this work we provide information on the particulate and gaseous emissions from two wood fired outdoor hydronic heaters. The units were tested using an integrated duty cycle test method that captured cold starts, reload, cyclic and modulating periods between 15 and 100% of maximum rated output. The data and results show a much higher emission factor than those reported by current certification test methods but are more representative of how the units operate in the field.

A Comprehensive Performance Characterization of a Nanofluid-Powered Dual-Fluid PV/T System under Outdoor Steady State Conditions

This paper discusses the effectiveness of simultaneous use of CuO nanofluid and air as a dual-fluid coolant for the thermal management of a photovoltaic/thermal (PV/T) system. Outdoor experimental studies were performed to calculate the discrepancies between indoor and outdoor test findings. The thermal efficiency and the electrical characteristics of the dual-fluid PV/T system were investigated under steady-state test conditions following ISO standards. It was found that the divergence in electrical efficiency between indoor and outdoor-based PVT testing was significantly higher, while the difference in thermal efficiencies was marginal. It was observed that nanofluid/air, even at the lowest flow rates, outclassed the water/air coolant at higher flow rates in terms of PV/T energy output, which also ultimately helps in reducing the energy requirement for pumping. Unlike conventional solar air heaters, the proposed dual-fluid PV/T system produces a high air temperature when operated with only air at stagnant nanofluid. The maximum PV/T efficiency of approximately 85% was recorded when the nanofluid and air flows were kept at 0.02 kg/s and 0.04 kg/s, respectively. It is concluded that outdoor steady state testing provides comprehensive performance characterization of the nanofluid powered dual-fluid coolant for the PV/T system.

Assessing the Impact of Lubricant and Fuel Composition on LSPI and Emissions in a Turbocharged Gasoline Direct Injection Engine

<div class="section abstract"><div class="htmlview paragraph">Downsized turbocharged gasoline direct injection (TGDI) engines with high specific power and torque can enable reduced fuel consumption in passenger vehicles while maintaining or even improving on the performance of larger naturally aspirated engines. However, high specific torque levels, especially at low speeds, can lead to abnormal combustion phenomena such as knock or Low-Speed Pre-Ignition (LSPI). LSPI, in particular, can limit further downsizing due to resulting and potentially damaging mega-knock events. Herein, we characterize the impacts of lubricant and fuel composition on LSPI frequency in a TGDI engine while specifically exploring the correlation between fuel composition, particulate emissions, and LSPI events. Our research shows that: (1) oil composition has a strong impact on LSPI frequency and that LSPI frequency can be reduced through a carefully focused approach to lubricant formulation. In addition, (2) we observed significant improvement potential in Brake Mean Effective Pressure (BMEP) achievable with zero LSPI events using both experimental and market-representative lubricant formulations. Finally, (3) fuels blended with high polyaromatic content were shown to increase LSPI frequency significantly; these fuels also caused a significant increase in particulate mass (PM) and particulate number (PN) emissions. In this paper, we discuss the above results along with the development and use of a high-fidelity test method to measure LSPI under steady-state test conditions.</div></div>

Characterization of uncertainty contributions in a high-accuracy PMU validation system

The effective deployment of Phasor Measurement Units (PMUs) in Distribution Networks (DNs) requires an enhancement in terms of estimation accuracy beyond the limits of IEEE Std C37.118.1 (IEEE Std), aiming at a Total Vector Error (TVE) in the order of 0.0x% in steady-state test conditions. As a consequence, a rigorous metrological characterization of PMU performance requires a validation system whose accuracy is at least one order of magnitude better than the one of the device under test, i.e. it requires a TVE in the order of 0.00x% in steady-state test conditions and 0.0x% in distorted or dynamic test conditions. In this paper, we consider the hardware and software architecture of a previously published PMU validation system specifically designed for PMUs operating in DNs. In this context, we evaluate the quality of the generated test waveforms, and we carry out a thorough metrological characterization of the uncertainty contributions due to generation, acquisition and synchronization stages. In this sense, the proposed analysis provides a rigorous methodology for the evaluation of such low uncertainty levels, and enables us to identify and discuss the most challenging aspects in the implementation of a high-accuracy PMU validation system.

Friction and wear of synchronizers in hand–shifted transmissions

The measurement of friction and wear on hand–shifted transmission synchronizers (highly loaded cone clutches) is carried out by two different test machines: 1. a steady state synchronization test stand: friction surface diameter: 40–80 mm; wear and the coefficient of friction are measured under steady state test conditions (i.e. axial force and speed are constant); 2. a non–steady state synchronization test stand: friction surface diameter: 90–170 mm; the synchronization process is simulated under the same non–steady state conditions as there are in a vehicle transmission; all parameters (for example axial force, speed, work and power loss due to friction) coincide on the test machine with those of a transmission in practical use; the synchronization process is measured and evaluated by plots. The friction surfaces are inspected by a stylus instrument (Perth–0–Meter) and by a scanning electron microscope. The influence of various parameters (for example friction materials, work and power loss due to friction, roughness and geometry of friction surface, lubricant, additive, etc.) on the friction and wear of the synchronizers can be determined. The methods of testing and the results obtained from the investigations will be presented in examples.

Phase extraction from interferograms with unknown tilt phase shifts based on a regularized optical flow method

A novel method is presented to extract phase distribution from phase-shifted interferograms with unknown tilt phase shifts. The proposed method can estimate the tilt phase shift between two temporal phase-shifted interferograms with high accuracy, by extending the regularized optical flow method with the spatial image processing and frequency estimation technology. With all the estimated tilt phase shifts, the phase component encoded in the interferograms can be extracted by the least-squares method. Both simulation and experimental results have fully proved the feasibility of the proposed method. Particularly, a flat-based diffractive optical element with quasi-continuous surface is tested by the proposed method with introduction of considerably large tilt phase shift amounts (i.e., the highest estimated tilt phase shift amount between two consecutive frame reaches 6.18λ). The phase extraction result is in good agreement with that of Zygo's MetroPro software under steady-state testing conditions, and the residual difference between them is discussed. In comparison with the previous methods, the proposed method not only has relatively little restrictions on the amounts or orientations of the tilt phase shifts, but also works well with interferograms including open and closed fringes in any combination.

Corrosion of V–Ti–Cr alloys in liquid lithium: influence of alloy composition and concentration of nitrogen in lithium

The effect of V–(0–70)Ti–(0–30)Cr (at.%) compositions on their compatibility with nitrogen-containing lithium (0.0015–0.67 at.% N) at 7000°C under steady-state test conditions and long-term contact with lithium (up to 2000 h) has been studied. The conditions for formation and stable coexistence of nitride layers on the surface of various compositions under variable nitrogen concentration in lithium have been defined. The V–(8–10)Ti–(4–5)Cr compositions showed the best characteristics from the standpoint of corrosion resistance, nitride layer stability under conditions of variable nitrogen concentration in lithium, and the possibility of ‘in situ’ protective nitride layer formation.

Stimulus compounding in pigeons

Two pigeons were trained on a three-ply multiple schedule in which reinforcement was available on a VI 1-min schedule for two of the components and extinction was in effect for the third component. SDs associated with reinforcement were either a tone or a light and the S△ associated with the extinction component was the absence of tone and light. After response rates stabilized, testing for summation was conducted with both steady-state and extinction test procedures. Both of these procedures involved 1-min presentations of the compound tone and light. Results indicate that summation did not emerge under the steady-state test conditions but did emerge under extinction test conditions.