This study investigates the techno-economic feasibility of solar-powered absorption cooling and heating systems for a large-sized hotel building in Sydney, Australia. The proposed plant primarily consists of evacuated tube solar collectors, a hot water storage tank, a single-effect absorption chiller, and a backup gas burner. Dynamic simulation of the system has been carried out using the TRNSYS environment. Several control strategies have been implemented in the model to increase the overall efficiency of the system. Solar fraction and levelized total cost of the system have been considered as energetic and economic indicators, respectively. The parametric study results reveal that the optimal values of the storage tank volume and specific collector area are 70 L/m 2 and 4 m 2 per kW cooling capacity of the chiller, corresponding to the solar fraction of ∼72% and levelized total cost of ∼874,000 AUD/year. Finally, the payback period of the solar equipment is calculated to be 30.8 years, reiterating this technology still needs a great deal of subsidy in order to be economically competitive with conventional air-conditioning systems.

A complete study for a solar dryer is shown. In this work the lemon drying process is considered. Also, results for temperature distribution, currents lines velocities and density distribution are presented inside of the dryer chamber. Curves for dried are obtained when the lost mass of the lemon is measured. For this purpose, a digital balance is used and during several intervals of time the measures are done. A Compact Field point device of National Instrument is used to measure temperatures inside of the chamber in the dryer. Thermocouples k-type were placed in different points. By acquisition data, the values of temperature were measured for the test. By means of software (ANSYS) is discretized the inner zone and using the temperatures as boundary conditions. Solving the system defined for the equations according to the mesh defined, temperature, velocities and densities are determined. The results allowing to identify what is the behavior inside of the dryer and how the drying process happens. This way to study the drying process can be useful when the behavior inside of the chamber wants to be evaluated. In addition, this work can be useful in the design of solar dryers because allows to know how the trays can be placed to take advantage in the best way the solar energy in solar dryers.

Milk spoilage is a common issue in remote dairy farms due to the unavailability of power grid. Many farmers rely on diesel engines to power their milk chillers. A sustainable approach is to replace the environmentally harmful diesel generators with solar powered chillers. Solar energy is attractive in such application because the peak cooling demand occurs at the peak solar irradiance. Solar energy can be converted to cooling through PV powered chiller or through thermally driven chillers. This concept was applied to a Modular Solar Bulk Milk Chiller (MilkPod™) which uses the solar energy to generate electricity in 6 kWp PV panels. The system cools 600 liters of milk per day as well as produces hot water for cleaning the milk tank. A detailed model was used in the design process and the system equipment were selected such that the system uses about 98% of its energy from the sun throughout the year. The effect of the solar energy utilization ratio, equipment supplied current as well as milk loading were investigated on the system performance.

In this work, four different arrangements of solar cooker box-type with internal reflectors results, for irreversibility and second law efficiency are presented. The solar cooker has two glasses in its cover to diminish the losses of heat radiation and convection, which in turn creates the hot house effect inside the cooker. The interior of the cooker has flat mirrors placed at different angles to reflect the solar radiation toward recipient with water. The obtained results are based on the heated water temperatures. These are obtained by means of numerical simulation, which in turn allows the comparison under identical conditions for the cookers. The results reveal that the energy reaching the cookers, less than 5%, is used in the water heating process. Most of the available energy is “stored” into the cooker glass cover, which shows the need for further work on improving cover materials in order to diminish such a situation.

As the demand for cooling increases in Canada, it creates a greater energy demand on the utility grid by placing peak loads during the summer months. As a result, air conditioning in the residential sector is responsible for a disproportionately large and increasing amount of CO 2 emissions in Canada. One potential solution is the use of solar thermally driven absorption chillers, however before their widespread use in Canada is possible, extensive testing and optimization of the systems must be conducted to determine their feasibility in the Canadian climate. This paper discusses a full scale experimental test rig that has been recently constructed and commissioned to experimentally evaluate the performance of a commercially available solar absorption chiller with integrated thermal storage. The complete system is described, including the system’s test capabilities, the instrumentation installed, the control system developed, and the calibration and uncertainty analysis completed on each individual sensor and the system as a whole. Additionally, the paper examines the charge cycle of the solar absorption chiller being studied, and compares the results to simulation results obtained from a TRNSYS model of the test apparatus.

A large solar hot water system can be utilized to provide driving energy for heating system, heat-driven cooling system, as well as to provide hot water. This research addresses the effects of the storage tank design parameters on the performance of a large-scale solar hot water system with a horizontal storage tank. Most literatures only considered the stratification performance of the thermal storage tank itself instead of considering the overall system performance. Also, there is lack of experimental research data available for the design purpose. Therefore, this study employs a numerical simulation technique to study the design parameters effect of a horizontal thermal storage tank on the performance of a large-scale solar hot water system. In this study, the ANSYS-CFX program is employed to calculate the flow and temperature distributions inside horizontal thermal storage tank. Then the inlets and outlets of the tank are combined with the TRNSYS program to simulate the entire system performance under the weather of three representative cities of Taiwan, (Taipei, Taichung and, Kaohsiung). The results of the present study indicate that the vertical stratification baffles in the tank have important effects on system performance improvement. Quantitative increase of solar fraction of the total load is obtained. The comparison with the system with vertical storage tank is provided. The results of the present study can provide important reference for the large solar hot water system design in improving system efficiency.

In order to meet global challenges to reduce greenhouse gas emissions, the implementation of solar systems for residential purposes is an emergent task. Commonly liquid-based solar systems are used to heat up shower and pool water. More recently space heating systems have become part of sustainable buildings. An alternative could be a solar system that uses air as energy carrier. This study analyses the retrofit of such a system into a 40-year-old building. Starting from the analysis of the energy demand of a selected room, a solar air heater was designed, simulated and evaluated experimentally. The solar efficiency of the constructed collector reached 60%.

Finding optimal operating conditions of solar-based power and cooling systems is always a challenge. Performance of these systems is highly dependent on several important parameters, which not only impact the long-term efficiency but also its technical and economic feasibility. This paper studies the operation/configuration problem of an ammonia-water power and cooling cycle using an exergetic analysis. Thermodynamic performance of the combined cycle was addressed by using analysis of variance and multiple linear regression analysis. Modeling was done in Matlab ® , using Refprop 9.0 to calculate the thermodynamic properties of the ammonia-water mixture. Convergence issues were observed on the thermodynamic properties estimation carried out by Refprop when the stream had high ammonia mass fraction. To solve this issue an averaging algorithm was implemented online to estimate such properties using pure ammonia data and high, but stable, ammonia concentration data. After this implementation, small differences between current and reference model were seen. Optimum operating conditions were obtained using response surface technique. The response variable used was the ratio between exergetic efficiency and exergy destruction. Results showed that the response variable is mainly influenced by the ammonia concentration, pressure ratio, turbine efficiency and temperature gradient in the heat exchanger. Finally integration of the power/cooling cycle with a solar field was performed using two types of concentrated solar collectors: Linear Fresnel Collector (LFC) and Parabolic Trough Collector (PTC). The analysis showed that LFC technology can be a viable alternative for small scale applications combined with power/cooling systems.

Energy use for space cooling has increased by 156% from 1990 to 2010 in the Canadian residential sector. In many parts of the country, the increasing use of electrically driven air-conditioners has begun to shift the peak load on the electricity grid from the coldest days of winter to the hottest days of summer. Many of Canada’s major electric utilities providers rely on fossil fuels to generate the additional capacity needed to meet the peak demand, resulting in significant greenhouse gas emissions. Solar-driven sorption chillers remain one of the possible solutions for shaving the peak loads experienced by the electricity grid. This paper presents a review of the recent developments in the research of adsorption and absorption chillers, as well as a comparison of the two technologies based on the latest published experimental results found in the literature. Adsorption chillers continue to evolve in their design, including the use of new consolidated and composite adsorbents, the integration of coated adsorbers into internal heat exchangers, and newly developed advanced cycles for heat and mass recovery. While the physical design of adsorption chillers continues to be advanced, the development of absorption chillers for solar cooling applications has largely been focused on optimizing the system as a whole through improved control strategies and the implementation of newly developed high performance solar collectors. Finally, the paper aims to assess the current state of development of solar-driven sorption chillers to provide insight into their applicability in the Canadian residential sector, as well as the remaining challenges facing this technology.

In ejector refrigeration cycles, ejector working fluids include various refrigerants with different properties. In some cases, ejector works with mixture of two different refrigerants; that each refrigerant have distinct properties. The purpose of this paper is to evaluate the performance of an ejector used for suction of a mixture of air and water vapor. In this regard, the ejector performance was numerically studied under the operating condition that a mixture of air and steam with variable mass fractions, were sucked into the ejector. With the help of numerical simulation, various conditions for two perfect gas streams of air and water vapor were investigated. Initially, the numerical simulation was carried out for the case that pure water vapor was considered as the working fluid of ejector. After validation of initial case with experimental data, numerical method was expanded for a specific case that, water vapor was considered as the working fluid of motive flow and a mixture of air and water vapor was considered for suction flow. Numerical simulations were done for different mass fraction of air and water vapor for suction flow mixture. Results indicated that, variations of the mass fraction of air in suction flow, leads to obvious changes in ejector performance. Also, it was observed that the increment of suction flow pressure, leads to increment of the ejector performance sensitivity to variations of suction flow mass fraction.

This paper proposes the design of a solar water bath heater for Central Power Plant in Assaluyeh region in south of Iran with the latitude of 27 °N. This heater uses flat plate solar collectors in an open circuit system. Solar intensity, absorbed radiation and ambient temperature are the regional parameters which are known to the designer. The temperature of the bath of water which is the outlet collector temperature (70 °C) belongs to the known parameters in the mentioned station. Flow rate, heat loss factor, the inlet temperature of the collector and the area which is the most important factor to evaluate the economical issues of the system are calculated with modeling the water bath with a shell and tube heat exchanger. The solar water bath heater is then simulated with TRNSYS software. The obtained results are in good agreement with analytical solution based on Duffie and Beckman method.

The research consisted in a conceptual and basic design of a prototype Stirling engine with the purpose of taking advantage of the solar radiation to produce electric energy. The work began with a bibliography review covering aspects as history, basic functioning, design configurations, applications and analysis methods, just to continue with the conceptual design, where the prototype specifications are determined. Finally, a basic dimensioning of the important components as heat exchangers (heater, cooler, and regenerator), piston, displacer and solar collector was elaborated. The principal conclusions were that the different analysis methods had dissimilitude between the results, in this sense, a construction of the prototype is necessary for the understanding of the complex phenomena occurring inside the engine.

A 35,000 ft 2 [3,251 m 2 ] Creative Arts instruction building is being constructed on the campus of Haywood Community College in Clyde, NC (∼25 miles [40 km] west of Asheville). The building’s HVAC system consists of a solar absorption chiller, two parallel back-up electric chillers, and radiant floor heating with condensing boiler back-up. Hot water is to be heated by 117 solar thermal panels with thermal energy storage in a 12,000 gallon [45,000 liters] insulated tank and service to both the absorption chiller and the radiant under-floor heating system. Peak cooling loads and unfavorable solar conditions are to be handled by parallel electric chillers, operated in sequence to achieve maximum performance. Emergency radiant under-floor heating hot water back-up is to be handled by gas-fired condensing boilers in the event of unavailable solar heated hot water. This paper will examine the extensive modeling process required of the system as performed in EnergyPlus, how preliminary modeling results influenced the control and design strategy, the annual behavior of the system and the importance of controllability.

The performance of an absorption solar cooling system operated under Taiwan climate is studied via computer simulation. Solar energy is utilized as the driving energy for an absorption cooling system, and a TRNSYS computer code is employed to simulate the operation of the system. Climate data in TMY2 form for five major cities of Taiwan are input to the simulation program. Also system operating parameters of solar collector area and the size of the storage tank are varied to study there effects on the system performance. This research provides computer simulation data for the monthly solar fraction (f) as well as the seasonal solar fraction (F) for the absorption solar cooling system operated under the climate of the major cities in Taiwan. The data can provide the design needs.

A class of solar-driven heat engines is modeled as a combined system consisting of a solar collector and a unified heat engine, in which muti-irreversibilities including not only the finite rate heat transfer and the internal irreversibility, but also radiation-convection heat loss from the solar collector to the ambience are taken into account. The maximum overall efficiency of the system, the optimal operating temperature of the solar collector, the optimal temperatures of the working fluid and the optimal ratio of heat transfer areas are calculated by using numerical calculation method. The influences of radiation-convection heat loss of the collector and internal irreversibility on the cyclic performances of the solar-driven heat engine system are revealed. The results obtained in the present paper are more general than those in literature and the performance characteristics of several solar-driven heat engines such as Carnot, Brayton, Braysson and so on can be directly derived from them.

The main propose of this research is providing a tool for suitable modeling, increase efficiency and decrease construction cost of solar absorption chiller. At first, the solar absorption chiller is modeled by the thermodynamic laws. Then, this model is converted to the new standard mathematical programming model with considering all technical and economic constrains. This mathematical model is optimized by Genetic algorithm (GA). After applying GA, optimized parameters of chiller heat exchanger designing and its electricity consumption are calculated. These parameters consist of heat exchanger effectiveness, heat transfer cross section area, heat transfer coefficient, efficiency of pump and motor. The effect of costs economic optimization is shown with comparing the optimum point and a system base case. It will be shown that for optimum point the total investment cost increases 2.0568% while the sum of destruction and loss exergy decreases 0.21% and annual cost decrease about 8.91% rather than base case. Coaling load of evaporator is related to an apartment with 50 m 2 Area in Tehran (case study).

A 4.2 kW solar furnace heliostat was interfaced with a closed-loop control system to manipulate the azimuth and elevation rotational degrees of freedom to continuously align a solar concentrator with the sun. A QP50-6SD2 quadrant photodiode laser beam positioning device, developed by Pacific Silicon and Sensor, was modified to sense the orientation of the sun. The quadrant photodiode was mounted inside a dark box with a pinhole aperture and mounted so that when the heliostat reflects light along the desired axis, the quadrant photodiode relays balanced error signals. These error signals were interpreted with a Basic Stamp 2p40 microcontroller developed by Parallax Inc. LM741 operational amplifiers and ADC0831 analog to digital converters were used for signal conditioning. The 2p40 microcontroller interprets and checks the error signals every 500ms and uses a ULN2803 Darlington Transistor array to activate the heliostat drive motor’s solid-state relays to maintain solar alignment. The closed-loop heliostat control system can track with 1.6 degrees of accuracy. This is closer than the original prediction of 3 degrees. The control system requires user-inputs for initial alignment. Alignment can initiate with the heliostat out of alignment by at least 6 degrees. The versatility of the 2p40 allows subroutines to be programmed in that can handle hysteresis in the slewing of the heliostat, continue tracking as the heliostat begins to wobble from wind gusts, or continue tracking during intermittent shadowing from clouds.

Data centers are facilities that primarily contain electronic equipment used for data processing, data storage, and communications networking. Regardless of their use and configuration, most data centers are more energy intensive than other buildings. The continuous operation of Information Technology equipment and power delivery systems generates a significant amount of heat that must be removed from the data center for the electronic equipment to operate properly. Since data centers spend up to half their energy on cooling, cooling systems becomes a key factor for energy consumption reduction strategies and alternatives in data centers. This paper presents a theoretical analysis of an absorption chiller driven by solar thermal energy as cooling plant alternative for data centers. Source primary energy consumption is used to compare the performance of different solar cooling plants with a standard cooling plant. The solar cooling plants correspond to different combinations of solar collector arrays and thermal storage tank, with a boiler as source of energy to ensure continuous operation of the absorption chiller. The standard cooling plant uses an electric chiller. Results suggest that the solar cooling plant with flat-plate solar collectors is a better option over the solar cooling plant with evacuated-tube solar collectors. However, although solar cooling plants can decrease the primary energy consumption when compared with the standard cooling plant, the net present value of the cost to install and operate the solar cooling plants are higher than the one for the standard cooling plant.

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%.

The objective of the present investigation is to develop generalized cumulative frequency distributions for hourly clearness indices applicable for different climates. The distributions have been developed in terms of suitable normalized variables relevant on hourly time scale, and include the swing (the difference between the maximum and minimum values of the hourly clearness index for a particular hour over the days in a month) in the hourly clearness index. The adequacy of the distributions developed in predicting the hourly clearness index has been established by comparing with the data values of the 183 secondary locations in addition to the 56 primary locations in USA for which the data are available.