Detailed Energy and Exergy Analysis for a Solar Lithium Bromide Absorption Chiller and a Conventional Electric Chiller (R134a)

2011 ◽  
Author(s):  
Yang Hu ◽  
Laura A. Schaefer ◽  
Volker Hartkopf
Keyword(s):  
Solar Collector ◽  
Exergy Analysis ◽  
Cooling System ◽  
Residential Buildings ◽  
Lithium Bromide ◽  
Building Energy ◽  
Hot Water ◽  
Exergy Destruction ◽  
Absorption Chiller ◽  
Two Stage

The Building Energy Data Book (2009) [1] shows that commercial and residential buildings in the U.S. consume 39.9% of the primary energy and contribute 39% of the total CO2 emissions. In the operation of buildings, 41.8% of building energy consumption is provided for building cooling, heating, domestic hot water, and ventilation for commercial buildings, while in residential buildings, this percentage increases to 58%. In energy system analysis, the energy approach is the traditional method of assessing the way energy is used in an operation. However, an energy balance provides no information on the degradation of energy or resources during a process. The concept of exergy combines the first law and second law of thermodynamics. The exergy analysis clearly quantifies the energy quality match between the supply and demand sides, and also addresses the exergy destruction (entropy generation) in each component. In this paper, a solar thermal driven absorption cooling system was analyzed for providing cooling to a building, the Intelligent Workplace South Zone at Carnegie Mellon University. The system includes a 52 m2 parabolic trough solar collector, and a 16 kW (4 tons) two-stage lithium bromide absorption chiller. The energy model and newly developed two-stage lithium bromide absorption chiller are programmed and integrated in Engineering Equation Solver (EES). The temperature, enthalpy, entropy, mass flow rate, and mass fraction of lithium bromide in the solar absorption system were presented in steady state operation. The exergy destruction in each component is calculated. The exergy destructions for the solar collector, generator, absorber, and heat exchangers were significantly higher than those in evaporator, condenser and expansion valves, the overall energy and exegetic efficiency were also calculated.

scholarly journals Advanced Exergy Analysis in the Dynamic Framework for Assessing Building Thermal Systems

Entropy ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 32 ◽  
Author(s):  
Ana Picallo-Perez ◽  
José M Sala ◽  
George Tsatsaronis ◽  
Saeed Sayadi
Keyword(s):  
Exergy Analysis ◽  
Energy System ◽  
Building Energy ◽  
Hot Water ◽  
Exergy Destruction ◽  
Dynamic Calculation ◽  
Thermal Systems ◽  
Dynamic Framework ◽  
Building Energy System ◽  
First Time

This work applies the Dynamic Advanced Exergy Analysis (DAEA) to a heating and domestic hot water (DHW) facility supplied by a Stirling engine and a condensing boiler. For the first time, an advanced exergy analysis using dynamic conditions is applied to a building energy system. DAEA provides insights on the components’ exergy destruction (ED) by distinguishing the inefficiencies that can be prevented by improving the quality (avoidable ED) and the ones constrained because of technical limitations (unavoidable ED). ED is related to the inherent inefficiencies of the considered element (endogenous ED) and those coming from the interconnections (exogenous ED). That information cannot be obtained by any other approach. A dynamic calculation within the experimental facility has been performed after a component characterization driven by a new grey-box modelling technique, through TRNSYS and MATLAB. Novel solutions and terms of ED are assessed for the rational implementation of the DAEA in building energy installations. The influence of each component and their interconnections are valuated in terms of exergy destruction for further diagnosis and optimization purposes.

scholarly journals A framework for the technical evaluation of residential buildings’ energy retrofit

2019 ◽  
Vol 111 ◽  
pp. 03025
Author(s):  
Annamaria Belleri ◽  
Chiara Dipasquale ◽  
Jennifer Adami
Keyword(s):  
Heat Pump ◽  
Energy Efficient ◽  
Cooling System ◽  
Residential Buildings ◽  
Building Energy ◽  
Energy Performance ◽  
Hot Water ◽  
Photovoltaic System ◽  
Performance Levels ◽  
Wide Range

Despite a wide range of energy-efficient technologies, financial products and public incentives are already available, the private as well as the public sector are struggling to invest in energy efficient solutions for buildings. The primary barriers are the high initial cost and the uncertain payback period of the energy refurbishment. Allowing for different scenario testing and considering interactions among different building energy systems, building energy simulation tools can help investors overcoming such barriers by offering support to the technical planning of energy refurbishment kits through quantitative information rather than qualitative. The energy performance and comfort of three reference multifamily residential buildings typologies were evaluated considering three envelope retrofitting performance levels (high-medium-low insulated and airtight) and different heating and domestic hot water systems (heat pump, boiler, district heating). The tested envelope retrofitting performance levels allow for heating need reduction between 50% and 90% compared to the reference case. The active cooling system is not accounted for and building energy simulations outputs include thermal comfort evaluation and overheating risk assessment during the summer season. The potential of photovoltaic system combined with heat pump is evaluated in the three reference cases leading to up to 30% of load coverage.

scholarly journals A Solar Heating and Cooling System in a Nearly Zero-Energy Building: A Case Study in China

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Zhifeng Sun ◽  
Yaohua Zhao ◽  
Wei Xu ◽  
Xinyu Zhang ◽  
Huai Li ◽  
...  
Keyword(s):  
Solar Collector ◽  
Cooling System ◽  
Water Storage ◽  
Building Energy ◽  
Solar Heating ◽  
Hot Water ◽  
Storage Tanks ◽  
Zero Energy ◽  
Heating And Cooling ◽  
Zero Energy Building

The building sector accounts for more than 40% of the global energy consumption. This consumption may be lowered by reducing building energy requirements and using renewable energy in building energy supply systems. Therefore, a nearly zero-energy building, incorporating a solar heating and cooling system, was designed and built in Beijing, China. The system included a 35.17 kW cooling (10-RT) absorption chiller, an evacuated tube solar collector with an aperture area of 320.6 m2, two hot-water storage tanks (with capacities of 10 m3 and 30 m3, respectively), two cold-water storage tanks (both with a capacity of 10 m3), and a 281 kW cooling tower. Heat pump systems were used as a backup. At a value of 25.2%, the obtained solar fraction associated with the cooling load was close to the design target of 30%. In addition, the daily solar collector efficiency and the chiller coefficient of performance (COP) varied from 0.327 to 0.507 and 0.49 to 0.70, respectively.

scholarly journals Energy and Exergy Analysis of Sensible Thermal Energy Storage—Hot Water Tank for a Large CHP Plant in Poland

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4842 ◽  
Author(s):  
Ryszard Zwierzchowski ◽  
Marcin Wołowicz
Keyword(s):  
Energy Storage ◽  
Ambient Temperature ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Exergy Analysis ◽  
Hot Water ◽  
Water Tank ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

The paper contains a simplified energy and exergy analysis of pumps and pipelines system integrated with Thermal Energy Storage (TES). The analysis was performed for a combined heat and power plant (CHP) supplying heat to the District Heating System (DHS). The energy and exergy efficiency for the Block Part of the Siekierki CHP Plant in Warsaw was estimated. CHP Plant Siekierki is the largest CHP plant in Poland and the second largest in Europe. The energy and exergy analysis was executed for the three different values of ambient temperature. It is according to operation of the plant in different seasons: winter season (the lowest ambient temperature Tex = −20 °C, i.e., design point conditions), the intermediate season (average ambient temperature Tex = 1 °C), and summer (average ambient temperature Tex = 15 °C). The presented results of the analysis make it possible to identify the places of the greatest exergy destruction in the pumps and pipelines system with TES, and thus give the opportunity to take necessary improvement actions. Detailed results of the energy-exergy analysis show that both the energy consumption and the rate of exergy destruction in relation to the operation of the pumps and pipelines system of the CHP plant with TES for the tank charging and discharging processes are low.

Simulation and Experimental Analysis of a Solar Driven Absorption Chiller With Partially Wetted Evaporator

2008 ◽  
Author(s):  
Jan Albers ◽  
Giovanni Nurzia ◽  
Felix Ziegler
Keyword(s):  
Cooling System ◽  
Cooling Water ◽  
Hot Water ◽  
Absorption Chiller ◽  
Efficient Operation ◽  
Part Load ◽  
Solar Cooling ◽  
Wetted Area ◽  
Solar Cooling System ◽  
Load Conditions

The efficient operation of a solar cooling system strongly depends on the chiller behaviour under part-load conditions since driving energy and cooling load are never constant. For this reason the performance of a single stage, hot water driven 30 kW H2O/LiBr-absorption chiller employed in a solar cooling system with a field of 350 m2 evacuated tube collectors has been analysed under part-load conditions with both simulations and experiments. A simulation model has been developed for the whole absorption chiller (Type Yazaki WFC-10), where all internal mass and energy balances are solved. The connection to the external heat reservoirs of hot, chilled and cooling water is done by lumped and distributed UA-values for the main heat exchangers. In addition to an analytical evaporator model — which is described in detail — experimental correlations for UA-values have been used for condenser, generator and solution heat exchanger. For the absorber a basic model based on Nusselt theory has been employed. The evaporator model was developed taking into account the distribution of refrigerant on the tube bundle as well as the change in operation from a partially dry to an overflowing evaporator. A linear model is derived to calculate the wetted area. The influence of these effects on cooling capacity and COP is calculated for three different combinations of hot and cooling water temperature. The comparison to experimental data shows a good agreement in the various operational modes of the evaporator. The model is able to predict the transition from partially dry to an overflowing evaporator quite well. The present deviations in the domain with high refrigerant overflow can be attributed to the simple absorber model and the linear wetted area model. Nevertheless the results of this investigation can be used to improve control strategies for new and existing solar cooling systems.

Architecture Design of Building Integrated Solar Collector

2014 ◽  
Vol 889-890 ◽  
pp. 1333-1336
Author(s):  
Yu Fu ◽  
Kai Chen ◽  
Fei Ying Fu ◽  
Xin Bin Wang
Keyword(s):  
Water Supply ◽  
Solar Collector ◽  
Residential Buildings ◽  
Radiation Energy ◽  
Hot Water ◽  
Space Heating ◽  
Solar Collectors ◽  
Domestic Hot Water ◽  
Heating And Cooling ◽  
Hot Water Supply

Solar thermal collector converts solar radiation energy into useful thermal energy and transfers to a transport fluid flowing through the system. The collected energy can be used either direct to space or water heating equipment, or to a thermal storage for later use. Along with fast development, not only domestic hot water supply is needed, but also space heating and cooling are required. Also, limited roof space is another key barrier that should be considered. Furthermore, most of the building integration with solar collectors are mounted on the roof top by flat or tilt angle at present. It is considered to be a failure of low level architectural quality because the collector is used only for application and seems as an independent technical element of the building. With the consideration of the above, novel type of solar collector has been proposed to realize the utilization and offset the barriers. This novel solar collectors is especially suitable to supply domestic hot water, and combines with ASHP for multi-function, space heating and cooling as well as domestic hot water supply. Additionally, it is well integrated with high-rise residential buildings, which is good for aesthetic.

scholarly journals flEECe, an energy use and occupant behavior dataset for net-zero energy affordable senior residential buildings

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Frederick Paige ◽  
Philip Agee ◽  
Farrokh Jazizadeh
Keyword(s):  
Affordable Housing ◽  
Energy Use ◽  
Residential Buildings ◽  
Building Energy ◽  
Hot Water ◽  
Occupant Behavior ◽  
Zero Energy ◽  
Net Zero Energy ◽  
Net Zero ◽  
Building Energy Use

AbstractThe behaviors of building occupants have continued to perplex scholars for years in our attempts to develop models for energy efficient housing. Building simulations, project delivery approaches, policies, and more have fell short of their optimistic goals due to the complexity of human behavior. As a part of a multiphase longitudinal affordable housing study, this dataset represents energy and occupant behavior attributes for 6 affordable housing units over nine months in Virginia, USA which are not performing to the net-zero energy standard they were designed for. This dataset provides researchers the ability to analyze the following variables: energy performance, occupant behaviors, energy literacy, and ecological perceptions. Energy data is provided at a 1 Hz sampling rate for four circuits: main, hot water heater, dryer, and HVAC. Building specifications, occupancy, weather data, and neighboring building energy use data are provided to add depth to the dataset. This dataset can be used to update building energy use models, predictive maintenance, policy frameworks, construction risk models, economic models, and more.

scholarly journals Air-source heat pump performance comparison in different real operational conditions based on advanced exergy and exergoeconomic approach

2020 ◽  
pp. 237-237
Author(s):  
Goran Vuckovic ◽  
Mirko Stojiljkovic ◽  
Marko Ignjatovic ◽  
Mica Vukic
Keyword(s):  
Heat Pump ◽  
Exergy Analysis ◽  
Residential Buildings ◽  
Performance Comparison ◽  
Hot Water ◽  
System Component ◽  
Exergetic Efficiency ◽  
Economic Point ◽  
Operational Conditions ◽  
Wide Range

The use of air-source heat pumps (ASHP) is increasing to meet the energy needs of residential buildings, and manufacturers of equipment have permanently expanded the range of work and improved the coefficient of performance (COP) in very adverse outdoor air conditions. However, in the time of a wide range of different technologies, the problem of using ASHP, from a techno-economic point of view, is constantly present. Although exergy is the only thermodynamic parameter compatible with economic principles, methods based on conventional exergy analysis are no longer able to respond to the extremely demanding needs of the actual market. Exergetic efficiency and exergoeconomic cost no longer provide sufficiently reliable information when it is necessary to reduce the investment costs or increase the energy/exergetic efficiency of the component/system. This paper presents a performance comparison of ASHP in different real operational conditions based on an advanced exergy and exergoeconomic approach. The advanced exergy analysis splits the destruction of exergy for each individual component of the heat pump into avoidable and unavoidable exergy destruction in order to fully understand the processes. In exergoeconomic performance evaluation, the information of stream costs is used as the information to calculate exergoeconomic variables associated with each system component. Irreversibilities in the compressor have the greatest impact on reducing the overall system exergetic efficiency by 46.7% during underfloor heating (UFH) operation and 24.53% during domestic hot water (DHW) operation. Exergy loss reduces exergetic efficiency by 5.72% (UFH) and 39.74% (DHW). High values of exergoeconomic cost for both operating regimes are present in flows 1, 2, 3 and 4 due to high costs of production and relatively small exergy levels. The general recommendation is to set the ASHP to operate with near-optimal capacities in both regimes and then reduce exergy of flows 1, 2, 5, 11 and 13.

Development of a Loss Method for Energy and Exergy Audit of Condensing Hot Water Boilers

2020 ◽  
pp. 1-23
Author(s):  
Mohsen Banifateme ◽  
Ali Behbahaninia ◽  
Saeed Sayadi
Keyword(s):  
Carbon Monoxide ◽  
Flue Gas ◽  
Residential Buildings ◽  
Direct Method ◽  
Hot Water ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Chemical Exergy ◽  
Carbon Monoxide Formation ◽  
Loss Method

Abstract Condensing boilers are used in commercial and residential buildings extensively. In this paper, a loss method is proposed to estimate the energy and exergy efficiencies of condensing hot water boilers. The presented method is based on the development of the method presented in ASME PTC 4.1. Energy loss terms consist of exhaust flue gas, carbon monoxide formation, radiation, and condensate outflow sensible heat. Exergy loss terms also include radiation losses, physical exergy of the exhaust flue gas, chemical exergy of the exhaust flue gas, increase in the chemical exergy of the flue gas due to carbon monoxide formation, condensate outflow exergy, boiler exergy destruction, and economizer exergy destruction. Energy and exergy efficiencies are calculated by estimation of these loss terms. To depict the method 's capability and compare results with the direct method, an experimental setup was designed and constructed. Results of energy and exergy audition of the boiler by applying the loss method are compared with the direct method. The results show that, although the condensing economizer improves energy efficiency, it does not improve the exergy efficiency significantly. The energy and exergy efficiencies were calculated 98.65 and 5.14 percent, respectively.

Comparison of Heat Transfer in Solar Collectors With Heat-Pipe Versus Flow-Through Absorbers

1987 ◽  
Vol 109 (4) ◽  
pp. 253-258 ◽  
Author(s):  
J. R. Hull
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Collector ◽  
Hot Water ◽  
Solar Collectors ◽  
Heat Transfer Characteristics ◽  
Absorption Chiller ◽  
Transfer Characteristics ◽  
Proper Design ◽  
Flow Through

Analysis of heat transfer in solar collectors with heat-pipe absorbers is compared to that for collectors with flow-through absorbers for systems that produce hot water or other heated fluids. In these applications the heat-pipe absorber suffers a heat transfer penalty compared with the flow-through absorber, but in many cases the penalty can be minimized by proper design at the heat-pipe condenser and system manifold. When the solar collector is used to drive an absorption chiller, the heat-pipe absorber has better heat transfer characteristics than the flow-through absorber.

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