Effect of the Power Generation Unit Operation on the Energy, Economical, and Environmental Performance of CCHP Systems for a Small Commercial Building

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.

2019 ◽  
Vol 109 ◽  
pp. 00065
Author(s):  
Yurii Oksen ◽  
Maksym Radiuk ◽  
Yurii Komissarov ◽  
Mykhailo Kirsanov

The possibility of increasing the efficiency of drying coal concentrate unit on the basis of pipe-dryers has been investigated by converting the heat of flue gases outlet into electrical energy and the heat potential of hot water supply system with a heat power generation unit operating on low-boiling working fluids. A method and an algorithm for calculating the thermal mode of the unit under the conditions of specified limitations on temperature pressures in heat exchangers have been developed. On the basis of mathematical modeling of thermal conditions, it has been found that under the conditions of PD-11 pipe-dryers, when the heat power generation unit operates with butane-pentane mixture, 204 kW of electricity can be generated with the condensation cycle, and 1780 kW of heat and 65 kW of electric energy can be generated with the heating cycle.


2019 ◽  
Vol 109 ◽  
pp. 00066
Author(s):  
Yurii Oksen ◽  
Olena Trofymova ◽  
Oleksandr Bobryshov ◽  
Anatolii Lukisha ◽  
Volodymyr Pryvalov

The schema for gas engine waste heat recovery to electrical power by dual circuit power generation unit with different working agents has been developed. The method and the most efficient power generation unit heat mode calculation algorithm under the conditions of the given restrictions on the temperature differences in the heat exchangers has been developed. Based on the mathematical modeling of heat modes it has been stated that 4200 kW of heat power can be utilized to generate 520 kW of electrical power for JMS 620 gas engine. It has been calculated that the efficiency of secondary heat recovery to electrical power reaches 12.3 % which leads general efficiency increase for a gas engine from 42.9 up to 50.0 %.


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.


2016 ◽  
Author(s):  
Harrison Warren ◽  
Alta Knizley ◽  
Pedro J. Mago

Combined heat and power (CHP) systems simultaneously generate on-site electricity and provide useful heat by utilizing waste heat from a power generation unit (PGU). CHP systems can enhance energy production efficiency and energy sustainability by reducing grid dependency, often yielding cost savings in the process. Furthermore, CHP systems can provide savings over conventional systems in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Typical CHP systems generate onsite power using a PGU, and the waste heat from the PGU is used to provide heating or hot water to the facility. Another variation for this system is to incorporate an organic Rankine cycle (ORC) to allow for increased potential reductions in operational cost, PEC, and CDE when compared to separate heat and power. This paper evaluates the effect of using electric energy storage on the performance of a PGU-ORC system. In the proposed system, the waste heat from a PGU is used to generate and to store electricity using an ORC coupled with electric energy storage (ES) (battery). Then, the electricity that is stored in the batteries could be used during the system operation at different times of the day so the PGU does not have to operate all the time. The PGU-ORC-ES system (with battery storage) is compared with a conventional system in terms of operational cost, PEC, and CDE. A restaurant building located in Chicago, IL is used to evaluate the potential of the proposed PGU-ORC-ES system. Results indicate that the addition of electric energy storage is beneficial to the proposed PGU-ORC system in terms of operational cost, PEC, and CDE. Furthermore, the effect of the size of the electric energy storage on the system performance is analyzed in this paper.


2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1143-1151 ◽  
Author(s):  
Karol Sztekler ◽  
Wojciech Kalawa ◽  
Sebastian Stefanski ◽  
Jaroslaw Krzywanski ◽  
Karolina Grabowska ◽  
...  

At present, energy efficiency is a very important issue and it is power generation facilities, among others, that have to confront this challenge. The simultaneous production of electricity, heat and cooling, the so-called trigeneration, allows for substantial savings in the chemical energy of fuels. More efficient use of the primary energy contained in fuels translates into tangible earnings for power plants while reductions in the amounts of fuel burned, and of non-renewable resources in particular, certainly have a favorable impact on the natural environment. The main aim of the paper was to investigate the contribution of the use of adsorption chillers to improve the energy efficiency of a conventional power plant through the utilization of combined heat and power waste heat, involving the use of adsorption chillers. An adsorption chiller is an item of industrial equipment that is driven by low grade heat and intended to produce chilled water and desalinated water. Nowadays, adsorption chillers exhibit a low coefficient of performance. This type of plant is designed to increase the efficiency of the primary energy use. This objective as well as the conservation of non-renewable energy resources is becoming an increasingly important aspect of the operation of power generation facilities. As part of their project, the authors have modelled the cycle of a conventional heat power plant integrated with an adsorption chiller-based plant. Multi-variant simulation calculations were performed using IPSEpro simulation software.


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