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Perovskite solar technology can produce economically viable photovoltaic devices due to low cost of materials and scalable manufacturing. Solution phase deposition of all active layers lends itself to roll-to-roll fabrication methods which are well-established and have production rates of several hundred square meters per minute. In this techno-economic analysis, the opportunity to scale at this production throughput is considered with manufacturing rates exceeding one gigawatt per year in a single plant. Intense pulsed light is used for the post deposition process to minimize costs associated with the footprint, equipment, and operation. The analysis is limited to the operation of a roll-to-roll manufacturing facility producing a perovskite solar film that can be incorporated into photovoltaic modules. Costs associated with materials, labor, and equipment are considered along with utilities determined from the fundamental engineering calculations. The results show that at very large-scale operations of several gigawatts, the costs to produce the solar films range between $0.04 and $0.10 per watt.

A flexible one-dimensional model was created in Python to determine the periodic steady state cooling power of an active magnetocaloric regenerator. Several features of the model provide advantages when performing large parametric studies. Geometry, material properties, and operation parameters are read in as input. Fluid flow and magnetization profiles are parameterized, and thermodynamic consistency is forced in magnetocaloric material properties. A dynamic time step is used, and three associated model constants are set to work over a wide range of input parameter combinations. Derivative gain is adjusted to minimize convergence time resulting in an average convergence time reduction of approximately 50%.

Previous computer simulations and bench-scale experiments showed that the heat pipe assisted solar wall had the potential for significantly improved performance relative to conventional passive space heating systems. To further test this potential, a full-scale prototype of the heat pipe system was designed, built and installed in a classroom on the University of Louisville campus in Louisville, KY. During the spring heating season of 2010 (January–April), maximum daily peak thermal efficiency was 83.7% and average daily peak thermal efficiency was 61.4%. The maximum hourly average room gain achieved during the season was 163 W/m2. On days with good solar insolation, the thermal storage was heated to temperatures sufficient to provide significant energy to the classroom – even during the coldest days of the season. During the longest period (4 days) of low insolation during the season, average hourly heat delivery to the room from storage remained positive, and was never less than 16.6 W/m2. During good insolation days following a period of consecutive low insolation days, thermal storage temperature was quickly restored to levels comparable to those obtained during consecutive good insolation days. Estimated heat removal factor * transmittance absorptance product FR(τα) and heat removal factor * overall loss coefficient FRUL values for the system were comparable to those for glazed liquid active collectors.

Performance was evaluated for a passive solar space heating system utilizing heat pipes to transfer heat through an insulated wall from an absorber outside the building to a storage tank inside the building. The one-directional, thermal diode heat transfer effect of heat pipes make them ideal for passive solar applications. Gains by the heat pipe are not lost during cloud cover or periods of low irradiation. Simplified thermal resistance-based computer models were constructed to simulate the performance of direct gain, indirect gain, and integrated heat pipe passive solar systems in four different climates. The heat pipe system provided significantly higher solar fractions than the other passive options in all climates, but was particularly advantageous in cold and cloudy climates. Parametric sensitivity was evaluated for material and design features related to the collector cover, absorber plate, heat pipe, and water storage tank to determine a combination providing good thermal performance with diminishing returns for incremental parametric improvements. Important parameters included a high transmittance glazing, a high performance absorber surface and large thermal storage capacity. An experimental model of the heat pipe passive solar wall was also tested in a laboratory setting. Experimental variations included fluid fill levels, addition of insulation on the adiabatic section of the heat pipe, and fins on the outside of the condenser section. Filling the heat pipe to 120% of the volume of the evaporator section and insulating the adiabatic section achieved a system efficiency of 85%. Addition of fins on the condenser of the heat pipe did not significantly enhance overall performance. The computer model was validated by simulating the laboratory experiments and comparing experimental and simulated data. Temperatures across the system were matched by adjusting the model conductances, which resulted in good agreement with the experiment.

Aerosol detection in HVAC duct components is a critical component of contaminant detection and analysis. Incorrect placement of a sensor inlet within the ductwork can have a significant, deleterious effect on capture efficiency and sample accuracy. Computational fluid dynamics studies were conducted of straight rectangular cross–section ductwork and a 90° bend to determine flow patterns and simulations of particulate injections were made at various locations across the inlet. The resultant particle distributions were analyzed to determine the optimal placement for a sensor inlet. The study demonstrated that, for the geometries studied, the optimal location for a sensor inlet is approximately ½ to ¾ of a duct diameter downstream from the interior corner of the bend, centred laterally within the duct, and at approximately ⅔ of the duct height. These results were experimentally verified using ductwork constructed in a laboratory environment using a polydisperse aerosol and commercial particle counter.

The focus of this paper is the development of a thermal, finite difference numerical model to describe one-dimensional upward flame spread on practical wall materials. Practical materials include composite materials and those that char, in addition to clean burning, homogeneous materials. A set of equations used in the model is developed and the methods for obtaining necessary “fire properties” are discussed. Some of the particular features of the model include the use of a correlation for flame heat feedback and the use of an experimentally measured mass loss rate to incorporate the burning characteristics of practical materials. A comparison of the numerical predictions with the experimental results for flame heights and temperatures are shown for Douglas fir particle board. The model correctly predicts trends but underpredicts the flame heights and pyrolysis height in the cases tested. Two additional cases are shown for materials for which experimentally measured heat release rate data are used in place of the mass loss rate data. The flame and pyrolysis height predictions are in much better agreement for these cases. Further efforts to obtain material property data that is appropriate for flame spread modeling is indicated by this work.

The overall objective of the project is to gain an understanding of the flame spread phenomenon under simulated surrounding fire conditions. In this phase of the project, emphasis is placed on obtaining experimental data for upward flame spread with applied external radiation on practical wall materials. A second phase (not yet reported) is the development of a numerical flame spread model and the experimental results presented here will be used for comparison with model predictions. Flame height, and in some cases pyrolysis height, were recorded as functions of time for 120 cm×30 cm samples; and these data were used to quantitatively investigate the effect of external radiation on several materials. Infrared heating panels were used to supply radiant fluxes of up to 15 kW/m 2 to the sample. Many wood-based materials do not exhibit flame spread to the top of the sample when ignited without applied external flux. With moderate levels of external radiation (5–10 kW/m 2 ), many of these materials sustained flame spread to the top of the sample. With increasing external radiation levels, flame spread was also more rapid. A comprehensive series of tests was run on particle board to investigate the effect of igniter strength, preheat of the sample, and sample thickness. Igniter strength was not a significant factor and did not cause the flame spread to be sustained; the effect of preheat, even at moderate levels of radiant flux, was important; and sample thickness had a slight effect, with thicker samples burning slower. Total heat feedback to the sample was measured and the maximum values for various samples are reported. Experimental data obtained in this project will be used to aid in the development and validation of a numerical flame spread model.

The Coulter technique enables rapid analysis of particles or cells suspended in a fluid stream. In this technique, the cells are suspended in an electrically conductive solution, which is hydrodynamically focused by nonconducting sheath flows. The cells produce a characteristic voltage signal when they interrupt an electrical path. The population and size of the cells can be obtained through analyzing the voltage signal. In a microfluidic Coulter counter device, the hydrodynamic focusing technique is used to position the conducting sample stream and the cells and also to separate close cells to generate distinct signals for each cell and avoid signal jam. The performance of hydrodynamic focusing depends on the relative flow ratio between the sample stream and sheath stream. We use a numerical approach to study the hydrodynamic focusing in a microfluidic Coulter counter device. In this approach, the flow field is described by solving the incompressible Navier-Stokes equations. The sample stream concentration is modeled by an advection-diffusion equation. The motion of the cells is governed by the Newton-Euler equations of motion. Particle motion through the flow field is handled using an overlapping grid technique. A numerical model for studying a microfluidic Coulter counter has been validated. Using the model, the impact of relative flow rate on the performance of hydrodynamic focusing was studied. Our numerical results show that the position of the sample stream can be controlled by adjusting the relative flow rate. Our simulations also show that particles can be focused into the stream and initially close particles can be separated by the hydrodynamic focusing. From our study, we conclude that hydrodynamic focusing provides an effective way to control the position of the sample stream and cells and it also can be used to separate cells to avoid signal jam.

External radiation in enclosure fires can significantly enhance flame spread and fire growth. One of the effects of external radiation is to increase the mass loss rate of the fuel, which in turn produces larger flames. In this work, a measurement of mass loss with and without applied radiation was made as a function of time for three types of materials: a plastic (polymethylmethacrylate), wood-based products (particle board and hardboard), and a paper-based product (cardboard). The levels of applied radiation ranged from 0 to nearly 12 kWm−2. The purpose of the investigation was to (1) quantitatively determine the effect of external radiation on the mass loss of various materials,(2) measure various parameters which may be used to characterize the mass loss rate history of the materials and (3) determine a method for expressing the mass loss rate as a function of time for input into numerical models. Higher levels of external radiation resulted in higher peak mass loss rates and quicker consumption of the material. Quantities which are useful for ranking the flammability of materials have been measured for the samples tested and are tabulated.

The focus of this project is on simulation and testing of a novel passive solar heating system that utilizes the one-way heat transfer of heat pipes to significantly improve heating performance relative to conventional passive solar systems. A set of programmed thermal networks were used to simulate the performance of several conventional passive solar heating systems, including direct gain, concrete wall indirect gain and water wall indirect gain, and the heat pipe system. Simulations performed for four US locations representing a range of winter temperatures and available insolation exhibited higher performance for the heat pipe system, particularly in cold climates with low insolation. A small-scale laboratory model was constructed and tested under controlled conditions to confirm simulated system component performance and to test a range of component variations. Measured system efficiency was 85.1 ± 0.72%. A full-scale prototype was constructed, installed and instrumented. Results from a 21-day period in April show a prototype thermal efficiency range from 60–75% and an average of 66.2%; and a 30-day period in October and November ranges from 60–85% with an average of 73.9%. An opaque cover over the prototype, periodically installed to minimize unwanted gains during the cooling season, reduced overall gains by an average of 75%.Copyright © 2010 by ASME