Assessing Energy Efficiency of High Pressure Regenerative Feedwater Heaters in a Heating Unit of a Cogeneration Plant

2015 ◽  
Vol 236 ◽  
pp. 14-25 ◽  
Author(s):  
Bogdan Pojawa
Keyword(s):  
Energy Efficiency ◽  
Environmental Protection ◽  
Combustion Products ◽  
Primary Energy ◽  
Cogeneration Plant ◽  
Heating Unit ◽  
Continuous Growth ◽  
Fuel Prices ◽  
Energy Company ◽  
Long Time

Broadly understood technological progress, growth of the world's population and striving of individual countries for economic growth cause increased demand for energy. That energy is mainly obtained conventionally, from mineral fuels [16]. Limited fuel resources and high demand for fuels, which accompanies the increased demand for energy, result in continuous growth of fuel prices and, what it involves, the price of energy [6,16]. Another effect of the increased production of energy results is also the increased emission of combustion products which are harmful for the natural environment, mainly CO2 and NOx [6,9,10,]. Because of the above-mentioned factors, the importance of the assessment of energy efficiency, at the stage of energy production, distribution and end use as well as the problem of environmental protection gain more and more importance [4,5,15]. The idea of energy efficiency lies not only in energy conservation but also in finding ways for the present activities of producers and consumers to require reduced demand for primary energy expressed in tonnes of oil equivalent [3,7,13,14,17,19,21]. Energy companies must therefore respect a number of legal regulations concerning energy efficiency and environmental protection [3,4,5,15]. An energy company such as a cogeneration plant may achieve an improvement of energy efficiency mainly as a result of energy cogeneration itself but also as a result of improving the efficiency of internal processes (energy transformations) in the producing unit (in this case heating unit). Ensuring the maximum possible energy efficiency of the internal processes within the heating unit requires performing constant assessment of the entire unit and its components [7,11,12,13]. Even though energy cogeneration has been in use for a long time now [7,12,21], the problem of conducting a running energy efficiency assessment of the components of the heating unit still remains open [12].

scholarly journals An Analysis of the Multi-Criteria Decision-Making Problem for Distributed Energy Systems

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2453 ◽  
Author(s):  
Yanbin Li ◽  
Shuangshuang Shao ◽  
Feng Zhang
Keyword(s):  
Decision Making ◽  
Energy Efficiency ◽  
Environmental Protection ◽  
Energy Systems ◽  
Primary Energy ◽  
Decision Makers ◽  
Multi Criteria Decision Making ◽  
Index Test ◽  
Distributed Energy ◽  
Decision Making Problem

Choosing a distributed energy system (DES) is a multi-criteria decision-making problem. Decision-makers should not only consider the cost of the system, but also consider the energy efficiency and environmental protection of the system. In order to help decision-makers choose the best DES, this paper designs seven different DESs based on specific examples, using five criteria: investment cost, operation cost, primary energy consumption, primary energy utilization, and yearly CO2 emission. Additionally, three methods of super-efficiency Data Envelopment Analysis (DEA), Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), and Complex Proportional Assessment (COPRAS) are used to evaluate the system priority and analyze the sensitivity under different decision-making scenarios. The results show that when decision-makers only consider cost factors, traditional systems are the best choice. However, renewable energy systems are the best choice when decision-makers consider energy efficiency and environmental protection rather than cost. Among them, the photovoltaic storage system is the best system in many decision-making scenarios, because of its comprehensive advantages in cost, energy efficiency, and environmental benefit. Simultaneously, the system’s prioritization of different decision-making methods is different. In this paper, according to the Spearman correlation index test, the results achieved from TOPSIS and COPRAS are relevant and feasible.

scholarly journals Experimental and Numerical Study of a Microcogeneration Stirling Unit under On–Off Cycling Operation

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 801
Author(s):  
Gianluca Valenti ◽  
Aldo Bischi ◽  
Stefano Campanari ◽  
Paolo Silva ◽  
Antonino Ravidà ◽  
...  
Keyword(s):  
Numerical Study ◽  
Thermal Storage ◽  
Primary Energy ◽  
Operational Cost ◽  
Cogeneration Plant ◽  
Economic Optimization ◽  
Viable Option ◽  
Heating Value ◽  
Energy Flows

Stirling units are a viable option for micro-cogeneration applications, but they operate often with multiple daily startups and shutdowns due to the variability of load profiles. This work focused on the experimental and numerical study of a small-size commercial Stirling unit when subjected to cycling operations. First, experimental data about energy flows and emissions were collected during on–off operations. Second, these data were utilized to tune an in-house code for the economic optimization of cogeneration plant scheduling. Lastly, the tuned code was applied to a case study of a residential flat in Northern Italy during a typical winter day to investigate the optimal scheduling of the Stirling unit equipped with a thermal storage tank of diverse sizes. Experimentally, the Stirling unit showed an integrated electric efficiency of 8.9% (8.0%) and thermal efficiency of 91.0% (82.2%), referred to as the fuel lower and, between parenthesis, higher heating value during the on–off cycling test, while emissions showed peaks in NOx and CO up to 100 ppm but shorter than a minute. Numerically, predictions indicated that considering the on–off effects, the optimized operating strategy led to a great reduction of daily startups, with a number lower than 10 per day due to an optimal thermal storage size of 4 kWh. Ultimately, the primary energy saving was 12% and the daily operational cost was 2.9 €/day.

scholarly journals Using adsorption chillers for utilising waste heat from power plants

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1143-1151 ◽  
Author(s):  
Karol Sztekler ◽  
Wojciech Kalawa ◽  
Sebastian Stefanski ◽  
Jaroslaw Krzywanski ◽  
Karolina Grabowska ◽  
...  
Keyword(s):  
Power Generation ◽  
Energy Efficiency ◽  
Power Plant ◽  
Power Plants ◽  
Waste Heat ◽  
Primary Energy ◽  
Simulation Software ◽  
Coefficient Of Performance ◽  
Low Grade ◽  
Adsorption Chiller

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.

scholarly journals ENERGY EFFICIENCY OF ENTERPRISES AS A KEY FACTOR IN THE DEVELOPMENT OF THE COUNTRY'S ECONOMY

10.23856/3304 ◽  
2019 ◽  
Vol 33 (2) ◽  
pp. 36-49
Author(s):  
Kateryna Andriushchenko ◽  
Lidiya Shergina ◽  
Vita Kovtun ◽  
Nataliia Revutska ◽  
Andrii Vashchyshyn
Keyword(s):  
Energy Efficiency ◽  
Alternative Energy ◽  
Fusion Energy ◽  
Primary Energy ◽  
State Regulation ◽  
Energy Sources ◽  
Alternative Energy Sources ◽  
Key Factor ◽  
Environmentally Safe ◽  
Energy Independence

The transition to alternative energy sources requires a long period, attracting significant investments in the process of creating and developing environmentally friendly fuels. Creating an environmentally safe, energy-efficient economy is a prerequisite for sustainable development of each country. The above-mentioned factors determine the relevance of the study of the problems of the functioning and development of energy, which is mainly due to the economic expediency of renewable energy and the requirements of the country's energy independence. The objective of the article is to determine the features of ensuring the energy efficiency of the Ukrainian economy using alternative energy sources. Research shows that the development of alternative energy will allow us to move away from the use of traditional fuels and create the prerequisites for the energy independence of countries. Taking into account the natural factors and the significant dependence of Ukraine on imported primary energy sources, it is determined that solving the problem of increasing energy efficiency of the economy is possible only with the stimulation of the use of alternative energy sources. The most promising sources of energy are identified, namely: biofuels, wind energy, geothermal energy, solar energy, solar thermal, controlled thermonuclear fusion, energy of tides and effluents. The recommendations for realization of such directions of the policy of the state regulation in the energy sphere as energy security, energy efficiency, energy saving are given.

scholarly journals ENERGY EFFICIENCY IN RESIDENTIAL BUILDINGS, LESS STRAIGHT FORWARD THEN PRESUMED

2018 ◽  
Vol 13 (1) ◽  
Author(s):  
Hugo Hens
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Energy Use ◽  
Low Voltage ◽  
Residential Buildings ◽  
Primary Energy ◽  
Heating And Cooling ◽  
Net Zero ◽  
Energy Conserving ◽  
New Construction

Since the 1990s, the successive EU directives and related national or regional legislations require new construction and retrofits to be as much as possible energy-efficient. Several measures that should stepwise minimize the primary energy use for heating and cooling have become mandated as requirement. However, in reality, related predicted savings are not seen in practice. Two effects are responsible for that. The first one refers to dweller habits, which are more energy-conserving than the calculation tools presume. In fact, while in non-energy-efficient ones, habits on average result in up to a 50% lower end energy use for heating than predicted. That percentage drops to zero or it even turns negative in extremely energy-efficient residences. The second effect refers to problems with low-voltage distribution grids not designed to transport the peaks in electricity whensunny in summer. Through that, a part of converters has to be uncoupled now and then, which means less renewable electricity. This is illustrated by examples that in theory should be net-zero buildings due to the measures applied and the presence of enough photovoltaic cells (PV) on each roof. We can conclude that mandating extreme energy efficiency far beyond the present total optimum value for residential buildings looks questionable as a policy. However, despite that, governments and administrations still seem to require even more extreme measurements regarding energy efficiency.

Sustainable energy solutions for thermal load in buildings - Role of heat pumps, solar thermal, and hydrogen-based cogeneration systems

2021 ◽  
pp. 1-25
Author(s):  
Praveen Cheekatamarla ◽  
Vishaldeep Sharma ◽  
Bo Shen
Keyword(s):  
Energy Efficiency ◽  
Renewable Energy ◽  
Carbon Footprint ◽  
Energy Demand ◽  
Primary Energy ◽  
Heat Pumps ◽  
Total Carbon ◽  
Coefficient Of Performance ◽  
Renewable Energy Resources ◽  
The Impact

Abstract Economic and population growth is leading to increased energy demand across all sectors – buildings, transportation, and industry. Adoption of new energy consumers such as electric vehicles could further increase this growth. Sensible utilization of clean renewable energy resources is necessary to sustain this growth. Thermal needs in a building pose a significant challenge to the energy infrastructure. Supporting the current and future building thermal energy needs to offset the total electric demand while lowering the carbon footprint and enhancing the grid flexibility is presented in this study. Performance assessment of heat pumps, renewable energy, non-fossil fuel-based cogeneration systems, and their hybrid configurations was conducted. The impact of design configuration, coefficient of performance (COP), electric grid's primary energy efficiency on the key attributes of total carbon footprint, life cycle costs, operational energy savings, and site-specific primary energy efficiency are analyzed and discussed in detail.

Energy Today

2010 ◽  
Author(s):  
Hewitt Crane ◽  
Edwin Kinderman ◽  
Ripudaman Malhotra
Keyword(s):  
Energy Use ◽  
Primary Energy ◽  
Energy Industry ◽  
Public Attention ◽  
Fuel Prices ◽  
Secondary Sources ◽  
Sudden Rise ◽  
Petroleum Companies ◽  
End Use ◽  
Electricity Shortage

The energy industry is one of the largest of the world’s industries and one that directly influences the lives of the vast majority of the world’s population. However, the industry’s day-to-day conduct generally receives minimal public attention. Such exceptional events as an embargo on fuel shipments, a sudden rise in fuel prices, a widespread electricity shortage or outage, the rare nuclear accident, or a massive hurricane that affects oil production do make the national news, of course, and often receive prolonged coverage. Yet the more common events such as refinery fires, oil tanker wrecks, pipeline leaks and explosions, and coal-mine disasters attract the attention of only a relatively few, and then too often only in passing. And while the public attention to its activities can be fleeting, the industry is massive. Its size and influence are often overlooked, and the investments required to produce our needed energy are difficult to calculate. Using Exxon-Mobil, the largest of the petroleum companies, as a model, we estimate that the depreciated capital costs for the production of oil, gas, and chemical products derived from them are about $2.5 trillion per CMO. New investments required could be twice as large. A lack of public knowledge and the consequent lack of political will can only exacerbate our general inability to understand the enormity of rapidly changing the resources and technologies this industry employs. We begin our analysis of the state of the energy industry by first distinguishing between primary and secondary sources of energy. Next we examine the overall production of energy by the different primary sources. We then discuss the production and consumption of energy in different regions across the globe. We also look at the per capita consumption in these regions because it is germane to the discussion in chapter 4 of the projections for future energy use. Finally, because more than 40% of primary energy is converted into secondary sources or energy carriers (mainly electricity) before its end use, we survey the different secondary energy sources and their markets.

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