Sodium thermal electrochemical converters (Na-TECs) offer a high efficiency advancement for converting thermal energy into electrical energy without moving parts. Since the cell operates using a Na pressure difference between the high temperature evaporator and the lower temperature condenser, a hermetic seal capable of maintaining that pressure difference is essential. This study looked at brazing of the ceramic electrolyte used in these cells, which is a β ”-alumina solid-electrolyte referred to as BASE. Since a literature search found no papers pertaining to brazing of BASE, knowledge from ceramic to metal brazing called widegap brazing was used. Specifically, the widegap brazing of α -alumina to nickel-based alloys. Initial brazing trials used a traditional inert atmospheric brazing technique with an Ar-H 2 gas mixture. However, the very low pO 2 atmosphere resulted in the destruction of the BASE layers due to the diffusion of carbon to the outer surface of the electrolyte during brazing. A new and radically different brazing technique called air brazing was then attempted. This brazing technique proved successful using the brazing alloy Ag-8CuO. Both Ag and Cu are not deleteriously affected by Na corrosion; thus, Ag-8CuO were a good choice for the braze alloy. Leak tests were performed on these cells to establish their hermeticity. This cell structure and brazing technique proved to be successful. Air brazing is an exciting joining operation for these types of cells.

This paper aims to evaluate the thermal performance and feasibility of integrating the Earth-Air Heat Exchanger (EAHE) with the building’s vapor compression air cooling system. In the proposed system, the ambient air is forced by an axial fan through an EAHE buried at a certain depth below the ground surface. EAHE uses the subsoil low temperature and soil thermal properties to reduce the air temperature. The outlet air from the EAHE was used for the purpose of cooling the condenser of the vapor compression cycle (VCC) to enhance its coefficient of performance (COP). The potential enhancement on the COP was investigated for two different refrigerants (i.e. R-22 and R410a) cooling systems. A mathematical model was developed to estimate the underground soil temperature at different depths and the corresponding outlet air temperature of EAHE was calculated. The obtained results showed that the soil temperature in Dubai at 4 meters depth is about 27°C and remains relatively constant across the year. In order to estimate the effect of using EAHE on the performance of the VCC system, a sample villa project was selected as a case study. The obtained results showed that EAHE system contributed efficiently to the COP of the VCC with an overall increase of 47 % and 49 % for R-22 and R410a cycles, respectively. Moreover, the calculated values were validated against Cycle_D simulation model and showed good agreement with a maximum deviation of 5%. The payback period for this project was found to be around two years while the expected life time is about 10 years which makes it an attractive investment.

This study evaluated the building cooling capacity of sky radiation, which was previously identified to have the greatest cooling potential among common ambient sources for climates across the US. [Robinson, et al. 2013b]. A heat pipe augmented sky radiator system was simulated by a thermal network with nine nodes, representing a thin polyethylene cover, white (ZnO) painted radiator plate [Duffie & Beckman 2013], condenser and evaporator ends of the heat pipe, thermal storage fluid (water), tank wall, room, sky and ambient air. Heat transfer between nodes included solar flux and sky radiation to cover and plate, wind convection and radiation from cover to ambient, radiation from plate to ambient, natural convection and radiation from plate to cover, conduction from plate to condenser or, two-phase heat transfer from evaporator to condenser, natural convection from evaporator to water and from water to tank wall, natural convection and radiation from tank wall to room, and overall heat loss from room to ambient. Nodal temperatures were simultaneously solved as functions of time using Typical Meteorological Year (TMY3) weather data. Auxiliary cooling was applied as needed to limit room temperature to a maximum of 23.9°C. For this initial investigation, a moderate climate (Louisville, KY) was used to evaluate the effects of radiator orientation, thermal storage capacity and cooling load to radiator area ratio, LRR. Louisville and two challenging climates (Miami, FL and New Orleans, LA) were then used to evaluate five cover configurations — zero, one and two covers with unconstrained temperature, and zero and one cover with temperature limited to the dew point of ambient air to simulate condensation on the cover. Results were compared to a Louisville baseline with LRR = 10 W/m 2 K, horizontal radiator and one cover with constrained temperature, which provided an annual sky fraction (fraction of cooling load provided by sky radiation) of 0.861. A decrease to 0.857 was found for an increase in radiator slope to 20°, and a drop to 0.833 for 53° slope (latitude + 15°, a typical slope for solar heating). These drops were associated with increases in average radiator temperature by 0.2°C for 20° and 1.5°C for 53°. A 25% decrease in storage capacity caused a decrease in sky fraction to 0.854. Sky fractions were 0.727 and 0.963 for LRR of 20 and 5, respectively. Sky fractions for the baseline system in Miami and New Orleans were 0.505 and 0.603, respectively. In all three climates, performance was little affected by constraining the cover temperature and by adding a second cover. These results confirm the potential for passive cooling of buildings by radiation to the sky. Climate, LRR and thermal storage capacity had strong effects on performance, while the cover configuration did not. Radiator slope had a surprisingly small impact, considering that the view factor to the sky at 53° tilt is less than 0.5.

Absorption Power Cycles (APCs) provide an interesting field within power cycles. The multicomponent mixture with variable temperature across boiling is employed as a working fluid. This has a potential for decreasing exergy loss associated with heat transfer during phase change processes (boiling and condensation). Absorption process has also an effect of lowering exhaust pressure of a turbine. The APCs hold a potential for heat recovery applications at very low temperatures, where constant temperature of boiling and condensation largely limits performance and economic effectiveness of Organic Rankine cycles (ORCs). Theoretical calculations show superiority of APC over extensive range of considered ORC working fluid. The advantage of APC further increases when air cooled condenser needs to be used instead of wet cooling tower. With the same boundary conditions for all cycles the APC provides higher utilization efficiency and power output at source temperatures below approximately 120 °C, for temperatures as low as 60 °C the net power output can be surpassed even more than three times. The proposed APC employs aqueous solution of salts considered generally for absorption cooling (Lithium Bromide, Lithium Chloride, Calcium Chloride) as a working fluid. Unlike ammonia used in mixture with water in Kalina APC or often ORC working fluids, used salts are non-toxic, environmentally friendly and pure water in expander simplifies its design. After summary of theoretical research from thermodynamics point of view are discussed principles, aspects and issues for design of single components of the cycle. Results of sizing are presented on two examples with 100 °C heat source. First one is 20 kW e unit using hot air as a heat source and air cooled condenser, second one is 500 kW e unit with heat source being pressurized water and using wet cooling tower heat rejection. Results show possibility of building relatively efficient system for even small power output with turbine isentropic efficiency nearly 80 % for the 20 kW e unit, but relatively large heat exchangers.

Fast pyrolysis is one method of creating bio-oil from biomass such as native prairie grasses, corn stover, and other organic commercial and industrial byproducts. In this study, fast pyrolysis of camelina ( Camelina sativa ) meal feedstock was performed in an auger-type reactor. End products of the processing consisted of bio-char and condensed vapor in the form of bio-oil (ranging from liquid to highly viscous tar-like products). The bio-oil produced in the reactor was collected and analyzed to determine the effects of reactor and condenser temperatures on the properties of the bio-oil produced. Five reactor temperatures and two condenser temperatures were investigated in this study. The rheological properties of the bio-oil samples were analyzed, water content was determined with the Karl Fisher method, energy content was measured with a bomb calorimeter, and acidity was determined using a total acid titration test. The aging characteristics of the bio-oil were also investigated at seven days, fourteen days, and twenty-eight days after the oil was created to determine what effect, if any, time had on the its properties. Preliminary results indicated that products of the camelina meal pyrolysis process were more uniform when compared to that of other feedstocks (e.g. carinata meal, corn stover), yielding more consistent bio-oil characteristics.

Water desalination and air conditioning consumes huge amount of energy that mostly come from fossil fuels, which produces harmful emissions detrimental to the environment. This work is concerned with the use of a new hybrid cooling and water desalination system driven by solar thermal energy. The system primarily consists of an evacuated tube solar collector, LiBr absorption chiller, and a humidification-dehumidification (HDH) unit. Seawater is used to cool the condenser and absorber of the chiller as well as the condenser of the HDH unit. The heat rejected by the absorber is used to drive the HDH unit. Thermodynamic model of the system has been formulated and simulated using engineering equation solver (EES) software. The results show that the coefficient of performance (COP) of the chiller nearly remain constant with increase in seawater temperature at the absorber inlet. The average COP of the chiller is found to be 0.76. The hybrid system efficiency increases with increase in the seawater temperature mainly due the effect of latent heat of water condensation. The rate of fresh water production increases with increase in the seawater inlet temperature. This resulted in a higher outlet temperature at the absorber exit, leading to a higher energy input to the HDH unit. Gained output ratio (GOR) increases with increase in seawater temperature. This is due to the direct proportionality of the GOR to the amount of fresh water produced. The results also revealed that increasing the flow rate of seawater causes the decrease in the fresh water production due to the corresponding decrease in the temperature of the seawater.

A rechargeable personal air-conditioning (RPAC) device was developed to provide an improved thermal comfort level for individuals in inadequately cooled environments. This device is a battery powered air-conditioning system with the phase change material (PCM) for heat storage. The condenser heat is stored in the PCM during the cooling operation and is discharged while the battery is charged by using the vapor compression cycle as a thermosiphon loop. The conditioned air is discharged towards a single person through adjustable nozzle. The main focus of the current research was on the development of the cooling system. A 100 W cooling capacity prototype was designed, built, and tested. The cooling capacity of the vapor compression cycle measured was 165.6 W. The PCM was recharged in nearly 8 hours under thermosiphon mode. When this device is used in the controlled built environment, the thermostat setting can be increased so that building air conditioning energy can be saved by about 5–10%.

The results of the study at hand may have implications for treatment of grease, lipid fractions, free fatty acids (FFA) and salts of FFA extracted from wastes of food industry, bio-refineries or sewage sludge as well as contaminated lipid containing forage. The goal of the study is, to prevent such contaminated wastes from entering the food chain. The following ways of treatment are proposed. Thermal conversion of waste fats from rendering plants or lipids in the presence of aluminosilicates of the zeolite family produce hydrocarbons with net calorific values in the range of 40–42 MJ/kg. NMR studies show aliphatic hydrocarbons as main product at T = 400°C. The spectrum of products is shifted to alkyl benzenes at T = 550°C. In case of sodium carbonate conversion is achieved in the presence of 5% water at T = 430 ± 20°C yielding mainly a liquid bio-crude with a low acid index, a mixture of non-condensable gases and minor amounts of coke. Rectification of bio-crude from animal fat produces 65.8% of hydrocarbon based bio-diesel and 13.3% of gasoline type hydrocarbons. Distillation curve for bio-diesel is in accordance with DIN EN 490. However, the gasoline fraction lacks low boiling hydrocarbons indicating the necessity for technical improvements of condensers. Sodium carbonate is found to be effective as well as being relatively inexpensive compared to zeolite catalysts. Finally, successful conversion of meat and bone meal to biochar is proved by solid-state 13 C-NMR.

Small scale solar thermal systems are increasingly investigated in the context of decentralized energy supply, due to favorable costs of thermal energy storage (TES) in comparison with battery storage for otherwise economical PV generation. The present study provides the computational framework and results of a one year simulation of a low-cost pilot 3kW el micro-Concentrated Solar Power (micro-CSP) plant with TES. The modeling approach is based on a dynamic representation of the solar thermal loop and a steady state model of the Organic Rankine Cycle (ORC), and is validated to experimental data from a test site (Eckerd College, St. Petersburg, Florida). The simulation results predict an annual net electricity generation of 4.08 MWh/a . Based on the simulation, optimization studies focusing on the Organic Rankine Cycle (ORC) converter of the system are presented, including a control strategy allowing for a variable pinch point in the condenser that offers an annual improvement of 14.0% in comparison to a constant condensation pinch point. Absolute electricity output is increased to 4.65 MWh/a . Improvements are due to better matching to expander performance and lower condenser fan power because of higher pinch points. A method, incorporating this control strategy, is developed to economically optimize the ORC components. The process allows for optimization of the ORC subsystem in an arbitrary environment, e.g. as part of a micro-grid to minimize Levelized electricity costs (LEC). The air-cooled condenser is identified as the driving component for the ORC optimization as its influence on overall costs and performance is of major significance. Application of the optimization process to various locations in Africa illustrates economic benefits of the system in comparison to diesel generation.

To experiment 20kW OTEC, the closed-cycle type of OTEC (Ocean Thermal Energy Conversion) was designed and manufactured. R32 (Difluoromethane, CH2F2) was used as the working fluid and a temperature of heat source and heat sink is 26°C, 5°C, respectively. The semi-welded type heat exchanger is applied for the evaporator and condenser and the cycle was designed for the gross power of 20kW. In the plate arrangement of the semi-welded type heat exchanger, one channel for working fluid is welded, and another channel for seawater is sealed by gasket. In this paper, various performance evaluations and experiments were carried out as constructing subminiature pilot plant of the OTEC and compared with the results of cycle analysis. In results, gross power of the turbine shows 20.1kW and cycle efficiency is 1.91% when heat source and heat sink is 26°C, 5°C. For the variation of temperature difference between the heat source and heat sink, when the temperature difference was 21°C, the gross power increased by about 33.3% from that when the temperature difference was 19 °C.

Fast pyrolysis is one method of creating bio-oil from biomass such as native prairie grasses, corn stover, and other organic commercial and industrial byproducts. In this study, fast pyrolysis of Brassica carinata meal, or simply carinata meal, was performed in an auger-type reactor. The bio-oil produced in the reactor was collected and analyzed to determine the effects of reactor and condenser temperatures on the properties of the bio-oil produced. Five reactor temperatures and two condenser temperatures were investigated in this research. The rheological properties of the bio-oil samples were analyzed, water content was determined with the Karl Fisher method, energy content was measured with a bomb calorimeter, and acidity was determined using a total acid titration test. The aging characteristics of the bio-oil were also investigated at seven days, fourteen days, and twenty-eight days after the oil was created to determine what effect, if any, time had on the its properties. Preliminary results indicate that any reactor temperature above 500°C produces bio-oils of similar composition, although with changes in yield. In addition, the short-term aging results of the bio-oils have shown insignificant changes in total acid number, water content, and energy content.

A unique solar technology that can be building-integrated, which harnesses both visible and infrared spectrums of solar radiation, utilizes direct and diffuse radiation to produce electricity and hot water, and delivers daylight, has been conceptualized. This technology is a three-in-one (named Tri-Sol), low/medium-concentration, building-integrated, skylight system for commercial buildings. However, this technology can be utilized for building facades and other building envelope components. A key component of the technology is linear Fresnel lenses. These lenses can be designed to be thin and light-weight. Sunlight, concentrated by the linear Fresnel lenses with a low-cost single axis tracker, focuses on a high-efficiency, thin Photo Voltaic (PV) strip that is in contact with a thermal absorber. Electricity produced by PV strips can be processed and distributed from an electric power management system. The thermal absorber houses a sealed heat pipe for cooling the PV strip and producing hot water. The water-cooled condenser section of the heat pipe is external to the skylight so that there is no issue of water leakage through the skylight. Hot water produced can be used for end-use, space heating, or absorption cooling. All diffuse light that cannot be concentrated by Fresnel lenses is delivered into the building interior space. A pre-prototype of Tri-Sol technology was designed and built at University of New Haven (UNH). Solar Testing and Training Laboratory (STTL) at UNH houses solar thermal collector equipment with a capability to perform Solar Rating and Certification Corporation (SRCC) tests. The Tri-Sol module was mounted on the SRCC test equipment at UNH and was tested outdoors to identify any issues or design enhancements.

The design of expanders for organic fluids is gaining an increasing attention due to the large opportunities opened by the ORC as a way to recover low grade heat. The possibility of recovering at least a fraction of the energy related to throttling in inverse cycles could have interesting relapses on the market of heating (heat pumps) and refrigeration machines. The main challenge to be faced is the management of a highly wet fluid (typical quality is in the 0–0.6 range), which puts off side dynamic expanders like turbines. For this reason, piston technology is proposed and analyzed. The potential recovery from the throttling of a 20 kW target domestic heat pump cycle is determined by modeling the real expansion cycle with two different codes, a commercial one (largely widespread and very easy to use) and a purposely developed one, which is much more customizable and may include different approaches to the physical behavior of the two–phase expansion. The results show interesting possibility of energy recovery from this generally wasted source, which opens the way to improvements of the heat pump COP from 4% to about 7%, depending on the working (i.e. seasonal) conditions. The analysis also points out the agreement in the results of two different adopted simulation tools (commercial AMESim ® and self-made customizable EES ® ), which can be thus considered valuable in the design, analysis and optimization of the proposed expander. Due to the biphasic nature of the working fluid, the performance of the expander is strongly influenced by the inlet conditions of the fluid from the condenser of the heat pump to the cylinders, such as throttling of the inlet/outlet valves and friction through the ducts. On the whole, this expander technology has very interesting chances to effectively manage fluids under highly wet conditions, like those related to the throttling from upper to lower pressure of inverse cycles.

Thermal performance of an improved passive solar heat pipe system was directly compared to that of a previous prototype. Simulated and experimental results for the first prototype established baseline performance. Subsequently, potential improvements were simulated, and a second prototype was built and tested along side the first. The system uses heat pipes for high rates of heat transfer into the building, and limited losses in the reverse direction. The evaporator section of each heat pipe is attached to a glass-covered absorber on the outside of a south wall, and the slightly elevated condenser section is either immersed in water in a thermal storage tank or exposed to air in the room. Two-phase flow occurs in the heat pipe only when the evaporator is warmer than the condenser, creating a thermal diode effect. Computer simulations showed that system performance could be improved by using thicker insulation between the absorber and the storage tanks, and by switching from a copper to a rubber adiabatic section, which both reduced heat losses to ambient from the storage tanks. Early morning heating was improved by exposing one of five condensers directly to room air, which also improved overall system efficiency. A copper solar absorber soldered to the copper evaporator section improved heat conduction compared to the previous aluminum absorber bonded to the copper evaporator. Together these modifications improved simulated annual solar fraction by 20.8%. The new prototype incorporating these changes was tested along side the previous prototype in a two-room passive solar test facility during January through February of 2013. Temperatures were monitored with thermocouples at multiple locations throughout the systems, in each room and outdoors. Insolation was measured by four pyranometers attached to the building. Results showed that the design modifications implemented for the new model increased thermal gains to storage and to the room, and decreased thermal losses to ambient. The load-to-collector ratio for the experiments was 2.7 times lower than for the simulations, which decreased the potential for experimental improvements compared to the simulated improvements. However, average daily peak efficiency for the new system was 85.0%, compared to 80.7% for the previous system. Furthermore, the average storage temperature over the entire testing period for the new model was 13.4% higher than that of the previous model, while the average room temperature over the same period was 24.6% greater for the new system.

Renewable energy systems operated by a thermal energy resource such as geothermal power plants and solar thermal power systems are demanding improvement in their condensation performance [Kutscher & Costenaro, 2009]. While their energy resources are naturally obtained at almost no cost, heat rejecting components become relatively expensive to maintain and operate. In this research, a heterogeneous condensing surface is proposed to enhance the condensation heat transfer coefficient in vapor-to-liquid heat exchangers. On its surface, parallel stripes with hydrophobic feature and ones without it alternate. The effect of the partially hydrophobic condensing surface on the dropwise condensation heat transfer of saturated steam on the flat plate copper surface is experimentally investigated. A vertical flat plat condenser is constructed to evaluate the performance of the heterogeneous condensing surface in comparison with a plain copper sample and a homogeneous hydrophobic-treated copper sample. Experimental results show that condensation heat transfer of steam on the homogeneous hydrophobic-treated sample is superior to that on the plain copper surface despite the fact that both the surfaces stably promote dropwise condensation. The heat transfer coefficients for the heterogeneous surface at lower subcooling temperatures, when its stripes situate horizontally, are as high as the heat transfer coefficients for the homogeneous hydrophobic-treated surface. The enhancement for the horizontal heterogeneous sample over the plain copper sample is approximately 100%. The heat transfer coefficient for the heterogeneous sample with its stripes being vertical at 4 K subcooling is 25% greater than that of the plain copper sample. Higher heat transfer coefficients are observed at lower subcooling temperatures for all the samples. The results and observations of this project suggest that the heterogeneous surface has the potential to enhance the heat transfer coefficients.

In this paper, we present the results of the design, fabrication, installation, and operation of a 20-kW OTEC (ocean thermal energy conversion) pilot plant. The results can be used as basic data for the design of commercial plants with capacities in excess of 40 MW. To perform an experiment on the 20 kW OTEC, a closed OTEC cycle was designed and fabricated at the Ocean Water Plant Research Center. The cycle utilizes surface ocean water as its heat source and deep ocean water as its heat sink. R32 (Difluoromethane, CH2F2) was used as the working fluid, and the temperature of the heat source and heat sink were 26°C and 5°C, respectively. A semi-welded-type heat exchanger was used as the evaporator and condenser, and the OTEC cycle was designed for a gross power of 20 kW. The advantages of the semi-welded-type heat exchanger include easy maintenance of the gasket-type heat exchanger and the rare leakage of the welded-type heat exchanger. The plate arrangement of the semi-welded-type heat exchanger comprised one welded channel for the working fluid and another gasket-type channel. The gross power of the turbine was determined to be 20.49 kW. The evaporating capacity was calculated as 1,020 kW, and the cycle efficiency was determined to be about 2.00%.

This paper presents an analysis of an organic Rankine cycle (ORC) with dry cooling system aided by an earth-coupled passive cooling system. Several organic fluids were considered as working fluids in the ORC in the temperature range of 125–200°C. An earth-air-heat-exchanger (EAHE) is studied for a location in the United States (Las Vegas) and another in India (New Delhi), to pre cool the ambient air before entering an air-cooled condenser (ACC). It was observed that the efficiency of the system improved by 1–3% for the system located in Las Vegas and fluctuations associated with temperature variations of the ambient air were also reduced when the EAHE system was used. A ground-coupled heat pump (GCHP) is also studied for these locations where cooling water is pre cooled in an underground buried pipe before entering a condenser heat exchanger in a closed loop. The area of the buried pipe and the condenser size are calculated per kW of power generation for various working fluids.

Subcooling of the refrigerant at the exit of the condenser in a vapor compression refrigeration system could be an effective method to improve the coefficient of performance (COP). This method allows the refrigerant entering the evaporator with a lower mass fraction of vapor and absorbs more heat in the evaporator. The effort in this paper investigates a solar based integrated system of an electricity-driven vapor-compression chiller (VC) and an absorption heat pump (ABS) to provide both heating and cooling to space. Thermodynamic and heat transfer models of the integrated system were developed to estimate the system performance. The modeling results showed the integrated system can achieve 40% of the reduction on electricity consumption and 66% of the improvement in cooling COP. Furthermore, the hot water supply temperature can reach 50.25°C. The models have also been used to conduct parametric sensitivity analysis. The key parameters which affect the performance of the system were the heat source temperature, the hot water return temperature, and the outdoor air flow rate. Hot water flow rate only has significant influence on the hot water supply temperature. Increasing the temperature and flow rate of the heat source can have benefits on both heating and cooling performance. However, increasing the outdoor air flow rate can only benefit on energy saving and cooling performance.

Chilled water systems constitute a major portion of energy consumption in air conditioning systems of the large buildings and process cooling of the manufacturing plants. These systems do not operate optimally in most of the cases because of the operating parameters set and/or the components used. The Chilled water system analysis tool software (CWSAT) is developed as a primary screening tool for energy evaluation. This tool quantifies the energy usage of the various chilled water systems and typical measures that can be applied to these systems to conserve energy. The tool requires minimum number of inputs to analyze the component-wise energy consumption and incurred overall cost. Both air-cooled and water-cooled systems can be analyzed with this tool; however, this paper focuses on water-cooled systems. The tool uses weather data of the chilled water system location and loading schedules to calculate the chilled water system energy consumption. The Air-Conditioning and Refrigeration Institute (ARI) standard 550/590 typical loading schedule is also incorporated for the chiller(s) loading. The tool is capable of comparing economics by analyzing the energy consumption and relevant cost of the existing system and the new system with cost reduction opportunities considered like: (1) increase chilled water temperature set point, (2) lowering the condenser cooing water supply temperature set point, (3) replace chiller(s), (4) Apply variable speed control to chilled and/or condenser water pumps, (5) upgrade cooling tower fan speed control, (6) Use free cooling when possible for water-cooled systems. The savings can be calculated separately for each cost reduction opportunity or can be combined. The economics comparison can be a primary decision criterion for further detailed engineering and cost analysis related with system changes. The comparison between actual system energy consumption and CWSAT results are also shown.

A 12′ by 24′ passive solar test building has been constructed on the campus of the University of Louisville. The building envelope is comprised of structural insulated panels (SIPs), 12″ thick, (R-value of 45 ft 2 F/Btu) for the floor and walls and 16″ (R-63) for the roof. The building is divided into two symmetrical rooms with a 12″ SIPs wall separating the rooms. All joints between panels are caulked to reduce infiltration. Each room contains one window (R-9) on the north side wall, and two windows (also R-9) facing south for ventilation and daylighting, but which will also provide some direct gain heating. The south wall of each room features an opening that will accommodate a passive solar heating system so that performance of two systems can be compared side-by-side. The overhang above the south openings is purposely left short to accommodate an awning to provide adjustable shading. The calculated loss coefficient (UA) for each room of the building is 6.07 W/K. Each room is also equipped with a data acquisition system consisting on an SCXI 1600 16 bit digitizer and an SCXI 1102B isolation amplifier with an SCXI 1303 thermocouple module. Pyranometers are placed on the south wall and the clerestory wall to measure insolation on the solar apertures. For initial tests, one room is equipped with an original heat pipe system previously tested in another building, while the other is equipped with a modified heat pipe system. Changes to the modified system include copper absorbers versus aluminum, an adiabatic section constructed of considerably less thermally-conductive DPM rubber than the copper used for the original design, and one of the five condenser sections of the heat pipes is exposed directly to the room air to provide early-morning heating. Experimental results will be compared to simulations with as-built building characteristics and actual weather data. Previous simulations with a load to collector ratio of 10 W/m 2 K, a defined room comfort temperature range between 65°F to 75°F, and TMY3 weather data for Louisville, KY, showed that the modified heat pipe wall design improves annual solar fraction by 16% relative to the original design.