Effect of the Power Generation Unit Size on the Energy Performance of Cooling, Heating, and Power Systems

Author(s):  
N. Fumo ◽  
P. J. Mago ◽  
L. M. Chamra

Cooling, Heating, and Power (CHP) systems are a form of distributed generation that can provide electricity while recovering waste heat to be used for space and water heating, and for space cooling by means of an absorption chiller. CHP systems improve the overall thermal energy efficiency of a building, while reducing energy consumption. Since energy conservation has implications on energy resources and environment, CHP systems energy performance should be evaluated based on building primary energy consumption. Primary energy consumption includes the energy consumed at the building itself (site energy) plus the energy used to generate, transmit, and distribute the site energy. The objective of this investigation is to determine the effect of the power generation unit (PGU) size on the energy performance of CHP systems. Since CHP systems energy performance varies with the building energy profiles, in this study the same building is evaluated for three different cities with different climate conditions. This paper includes simulation results for the cases when a CHP system operates with and without a primary energy strategy. Results show that for any PGU size energy savings are guaranteed only when the primary energy strategy is applied. Since CHP system energy performance depends on the building energy use profiles, which depend on climate conditions and other factors such as building characteristic and operation, each case requires a particular analysis in order to define the optimum size of the power generation unit.

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2538
Author(s):  
Praveen K. Cheekatamarla

Electrical and thermal loads of residential buildings present a unique opportunity for onsite power generation, and concomitant thermal energy generation, storage, and utilization, to decrease primary energy consumption and carbon dioxide intensity. This approach also improves resiliency and ability to address peak load burden effectively. Demand response programs and grid-interactive buildings are also essential to meet the energy needs of the 21st century while addressing climate impact. Given the significance of the scale of building energy consumption, this study investigates how cogeneration systems influence the primary energy consumption and carbon footprint in residential buildings. The impact of onsite power generation capacity, its electrical and thermal efficiency, and its cost, on total primary energy consumption, equivalent carbon dioxide emissions, operating expenditure, and, most importantly, thermal and electrical energy balance, is presented. The conditions at which a cogeneration approach loses its advantage as an energy efficient residential resource are identified as a function of electrical grid’s carbon footprint and primary energy efficiency. Compared to a heat pump heating system with a coefficient of performance (COP) of three, a 0.5 kW cogeneration system with 40% electrical efficiency is shown to lose its environmental benefit if the electrical grid’s carbon dioxide intensity falls below 0.4 kg CO2 per kWh electricity.


2021 ◽  
Vol 9 (1) ◽  
pp. 6
Author(s):  
Diego Fernández-Cheliz ◽  
Eloy Velasco-Gómez ◽  
Juan Peral-Andrés ◽  
Ana Tejero-González

In Europe, primary energy consumption in buildings accounts for up to 25–40%, depending on the climate conditions. Space heating and Domestic Hot Water (DHW) contribute significantly to this energy consumption. Among the most common sources for heat generation in these appliances is natural gas. Condensing boilers can surpass the 100% energy performance over the lower heating value, if the operating conditions enable the water vapor in the exhaust gases to condensate. Consequently, optimizing the operating parameters of condensing boilers is necessary to decrease fuel consumption without hindering water heating needs. The present work presents an experimental approach to the operating parameters of a condensing boiler that works with natural gas. The aim is to develop a theoretical model that relates the energy performance to the water temperature set by the final user and the excess air set by the maintenance staff.


Author(s):  
N Fumo ◽  
P J Mago ◽  
L M Chamra

Combined cooling, heating, and power (CCHP) systems have the ability to optimize fuel consumption by recovering thermal energy from the prime mover of the power generation unit (PGU). Design of a CCHP system requires consideration, among other variables, of CCHP system components size and type. This study focuses on the analysis of hybrid-cooling, heating, and power (hybrid-cooling CCHP) systems that have an absorption chiller (CH) and a vapour compression system to handle the cooling load. The effect of the size of both cooling mechanisms is analysed in conjunction with the PGU size and efficiency. For better energy performance analysis simulations, results are presented based on the building-CCHP system primary energy consumption (PEC). Hybrid-cooling CCHP systems yield higher primary energy reduction than CCHP systems with an absorption CH alone. To account for the effect of climate conditions, hot and cold climates were considered by performing simulations for Tampa and Chicago weather conditions. The results are presented in tabular form to show the value of the PEC reduction as a function of the PGU size and efficiency, and the size of the absorption CH.


2020 ◽  
Vol 12 (9) ◽  
pp. 3566
Author(s):  
Byung Chang Kwag ◽  
Sanghee Han ◽  
Gil Tae Kim ◽  
Beobjeon Kim ◽  
Jong Yeob Kim

The purposes of this study were to overview the building-energy policy and regulations in South Korea to achieve energy-efficient multifamily residential buildings and analyze the effects of strengthening the building design requirements on their energy performances. The building energy demand intensity showed a linear relationship with the area-weighted average U-values of the building envelope. However, improving the thermal properties of the building envelope was limited to reducing the building-energy demand intensity. In this study, the effects of various energy conservation measures (ECMs) on the building-energy performance were compared. Among the various ECMs, improving the boiler efficiency was found to be the most efficient measure for reducing the building-energy consumption in comparison to other ECMs, whereas the building envelope showed the least impact, because the current U-values are low. However, in terms of the primary energy consumption, the most efficient ECM was the lighting power density because of the different energy sources used by various ECMs and the different conversion factors used to calculate the primary energy consumption based on the source type. This study showed a direction for updating the building-energy policy and regulations, as well as the potential of implementing ECMs, to improve the energy performances of Korean multifamily residential buildings.


Author(s):  
Anna K. Hueffed ◽  
Pedro J. Mago ◽  
Louay M. Chamra

Combined cooling, heating, and power (CCHP) systems generate electricity at or near the place of consumption and utilize the accompanying waste heat to satisfy the building’s thermal demand. CCHP systems have often been cited as advantageous alternatives to traditional methods of power generation and one of the critical components affecting their performance is the power generation unit (PGU). This investigation examines the effect of the PGU on the energy, economical, and environmental performance of CCHP systems. Different size PGUs are simulated under the following operational strategies: follow the building’s electric load, follow the building’s thermal load, and operate at constant load. An internal combustion engine is used as the PGU in the CCHP system to meet hourly electric, cooling, heating, and hot water loads of a typical office building for a year. Annual operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE) are found for two cities and compared to a conventional building. Finally, a simple optimization is performed to determine the best engine load for each hour during the simulation. Among the results, the smallest engine generally yielded the lowest costs and lowest PEC; but, no such trend was found with regards to CDE.


2011 ◽  
Vol 32 (3) ◽  
pp. 33-43 ◽  
Author(s):  
Jakub Kupecki ◽  
Krzysztof Badyda

SOFC-based micro-CHP system as an example of efficient power generation unit Microscale combined heat and power (CHP) unit based on solid oxide fuel cells (SOFC) for distributed generation was analyzed. Operation principle is provided, and the technology development in recent years is briefly discussed. System baseline for numerical analysis under steady-state operation is given. Grid-connected unit, fuelled by biogas corresponds to potential market demand in Europe, therefore has been selected for analysis. Fuel processing method for particular application is described. Results of modeling performed in ASPEN Plus engineering software with certain assumptions are presented and discussed. Due to high system electrical efficiency exceeding 40%, and overall efficiency over 80%, technology is an example of highly competitive and sustainable energy generation unit.


2021 ◽  
Vol 11 (2) ◽  
pp. 542
Author(s):  
Jaqueline Litardo ◽  
Massimo Palme ◽  
Rubén Hidalgo-León ◽  
Fernando Amoroso ◽  
Guillermo Soriano

This paper compares the potential for building energy saving of various passive and active strategies and on-site power generation through a grid-connected solar photovoltaic system (SPVS). The case study is a student welfare unit from a university campus located in the tropical climate (Aw) of Guayaquil, Ecuador. The proposed approach aims to identify the most effective energy saving strategy for building retrofit in this climate. For this purpose, we modeled the base line of the building and proposed energy saving scenarios that were evaluated independently. All building simulations were done in OpenStudio-EnergyPlus, while the on-site power generation was carried out using the Homer PRO software. Results indicated that the incorporation of daylighting controls accounted for the highest energy savings of around 20% and 14% in total building energy consumption, and cooling loads, respectively. Also, this strategy provided a reduction of about 35% and 43% in total building energy consumption, and cooling loads, respectively, when combined with triple low-e coating glazing and active measures. On the other hand, the total annual electric energy delivered by the SPVS (output power converter) was 66,590 kWh, from where 48,497 kWh was supplied to the building while the remaining electricity was injected into the grid.


2018 ◽  
Vol 882 ◽  
pp. 215-220
Author(s):  
Matthias Koppmann ◽  
Raphael Lechner ◽  
Tom Goßner ◽  
Markus Brautsch

Process cooling and air conditioning are becoming increasingly important in the industry. Refrigeration is still mostly accomplished with compression chillers, although alternative technologies are available on the market that can be more efficient for specific applications. Within the scope of the project “EffiCool” a technology toolbox is currently being developed, which is intended to assist industrials users in selecting energy efficient and eco-friendly cooling solutions. In order to assess different refrigeration options a consistent methodology was developed. The refrigeration technologies are assessed regarding their efficiency, CO2-emissions and primary energy consumption. For CCHP systems an exergetic allocation method was implemented. Two scenarios with A) a compression chiller and B) an absorption chiller coupled to a natural gas CHP system were calculated exemplarily, showing a greater overall efficiency for the CCHP system, although the individual COP of the chiller is considerably lower.


2014 ◽  
Vol 30 (4) ◽  
pp. 37-50 ◽  
Author(s):  
Jacek Kamiński

Streszczenie W artykule przedstawiono model matematyczny, który możne być zastosowany do badań i analiz dotyczących zużycia energii pierwotnej w sektorze energetycznym dla różnych struktur rynkowych. Choć problematyka ta była już przedmiotem badań w kontekście regulacji środowiskowych czy postępu technologicznego, według najlepszej wiedzy autora wcześniejsze prace nie omawiały problematyki zużycia paliw pierwotnych w zależności od struktur rynkowych. W artykule sfor- mułowano model matematyczny, który umożliwia takie analizy. Model jest oparty na koncepcji teorii gier - zastosowano podejście Coumota z uwzględnieniem oczekiwanych zmian (Conjectural Yariations - CV). Model został sformułowany jako problem programowania mieszanego komple- mentarnego (Mbced Complementarity Problem - MCP), który szczególnie nadaje się do modelowania systemów paliwowo-energetycznych w kontekście rynkowym. Przyjęto założenie o uwzględnieniu dwóch hurtowych rynków obrotu energią elektryczną, a mianowicie rynku dnia następnego (RDN) oraz rynku bilateralnego (OTC). Model może być zaimplementowany w dowolnym systemie mode- lowania wykorzystywanym do budowy matematycznych modeli systemów paliwowo-energetycz- nych. Oprócz analiz zużycia energii pierwotnej w sektorze energetycznym model będzie mógł być również wykorzystany do analiz ekonomicznych, w szczególności analiz dobrobytu konsumentów i producentów, strat społecznych oraz cen i wielkości produkcji. Badania przedstawione w niniejszym artykule będą kontynuowane, w szczególności w zakresie pozyskania danych i kalibracji modelu. `


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