Second Generation Integrated Combined Heat and Power Engine Generator and Liquid Desiccant System

2004 ◽  
Author(s):  
Sandeep Nayak ◽  
Sumit Ray ◽  
Reinhard Radermacher
Keyword(s):  
Power Generation ◽  
Thermal Energy ◽  
Second Generation ◽  
Waste Heat ◽  
Water Solution ◽  
Combined Heat And Power ◽  
Total System ◽  
Generation Process ◽  
Liquid Desiccant ◽  
Chp System

The Combined Heat and Power (CHP) concept is aptly suited to improve or eliminate some of the global and local issues concerning electric commercial buildings. CHP involves on-site or near-site generation of electricity by using gas-fired equipment along with utilization of thermal energy available from the power generation process. CHP has the potential of providing a 30% improvement over conventional power plant efficiency and a CO2 emissions reduction of 45% or more. In addition, an overall total system efficiency of 80% can be achieved because of the utilization of thermal energy, that would otherwise be wasted, and the reduction of transmission, distribution and energy conversion losses. CHP technology also makes cost savings possible by reducing high summertime electrical demand charges while at the same time providing necessary space heating and cooling. Savings are further increased in applications where waste heat can replace electric heating. Moreover, CHP has the ability to address indoor air quality issues when utilizing a desiccant dehumidifier by providing direct humidity control and consequently reducing the potential for mold and bacteria development. Because power generation is done on-site, CHP provides control in meeting a building’s electrical needs and also provides an increased level of reliability to ensure high employee productivity. The current research is being carried out in a four–story commercial office building that has been established as the CHP research and demonstration facility on the campus of the University of Maryland in College Park, MD, USA. The 52,700 square feet administrative building includes two heating, ventilating and air-conditioning (HVAC) zones of equal area where zone 1 includes the first and second floors and zone 2 includes the second and third floors. This has facilitated the installation of two different CHP systems for the two zones. The research in this paper discusses about the CHP system catering to zone 1. This paper describes a second generation CHP system involving the integration of a new 75 kW commercial engine generator with the existing liquid desiccant system. The engine generator is connected parallel to the grid for supplying 75 kW of electrical power to the building while the combined waste heat recovered from the exhaust gases as well as the jacket water from the engine is used to heat a 50:50 ethyl glycol–water loop through a packaged heat recovery system. This recovered heat is then used for the regeneration of the lithium chloride solution in a liquid desiccant system and the ethyl glycol–water solution is returned back to the engine. The liquid desiccant system reduces the latent load of the ventilation air entering the roof top unit. Technical challenges concerning electrical and control aspects that were related to modifications of the original CHP system are described and improvements to the original system design and performance are evaluated. The paper then discusses the experimental results obtained with first generation CHP system and its overall performance.

Impact of CHP System Component Efficiencies on the Economic Benefit of CHP Systems Using Spark Spread Analysis

2011 ◽  
Author(s):  
Amanda D. Smith ◽  
Pedro J. Mago ◽  
Nelson Fumo
Keyword(s):  
Sensitivity Analysis ◽  
Thermal Energy ◽  
Waste Heat ◽  
System Component ◽  
Cost Ratio ◽  
Total System ◽  
System Efficiency ◽  
Conventional System ◽  
Chp System ◽  
The Cost

A combined heating and power system (CHP) can take the place of a conventional system with separate heating and power (SHP) where electricity is purchased from the grid. The CHP system provides electrical energy through a prime mover located near the building it serves, and waste heat from this generation is captured and delivered to the building to provide thermal energy. For a CHP system to show an economic advantage over a conventional system, its operating costs must be lower when providing the same amount of thermal energy and electricity that would have come from the SHP system. The spark spread (SS), or price difference between purchased electricity and fuel, is used as a simple indicator as to whether the CHP system is economically viable. Rather than using a single value of SS as a cutoff for viability of the CHP system, a more detailed spark spread expressed in terms of the efficiencies of the CHP system and SHP system components can be used to determine if a CHP system is economically viable. In an initial feasibility study, the calculation of the SS is based on estimates of a number of variables. It is important to assess the likely impact of changes in certain of some of these variables, as such changes can affect the SS calculations. This paper presents a sensitivity analysis to determine the effects of different parameters on the cost ratio which is used to calculate SS, including: reference heating system efficiency, power generation unit (PGU) efficiency and CHP overall system efficiency. Because CHP system efficiency itself is a function of the PGU efficiency as well as the thermal efficiency, these two parts of the total system efficiency are also investigated separately. Since the cost of purchased electricity and fuel varies by geographic region, the required spark spread for a given system may indicate favorable economics for a CHP system in one location while the CHP system shows no potential for savings in another location. Therefore, the sensitivity analysis is considered for three different U.S. locations.

scholarly journals Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2487 ◽  
Author(s):  
Heng Chen ◽  
Zhen Qi ◽  
Qiao Chen ◽  
Yunyun Wu ◽  
Gang Xu ◽  
...  
Keyword(s):  
Power Generation ◽  
Flue Gas ◽  
Waste Heat ◽  
Heating System ◽  
Combined Heat And Power ◽  
Back Pressure ◽  
Coal Consumption ◽  
Heating Capacity ◽  
Boiler Efficiency ◽  
Saving Effect

A conceptual high-back pressure (HBP) heating system cooperating raw coal pre-drying for combined heat and power (CHP) was proposed to improve the performance of the HBP-CHP unit. In the new design, besides of heating the supply-water of the heating network, a portion of the exhaust steam from the turbine is employed to desiccate the raw coal prior to the coal pulverizer, which further recovers the waste heat of the exhaust steam and contributes to raising the overall efficiency of the unit. Thermodynamic and economic analyzes were conducted based on a typical 300 MW coal-fired HBP-CHP unit with the application of the modified configuration. The results showed that the power generation thermal efficiency promotion of the unit reaches 1.7% (absolute value) owing to suggested retrofitting, and meanwhile, the power generation standard coal consumption rate is diminished by 5.8 g/kWh. Due to the raw coal pre-drying, the energy loss of the exhaust flue gas of the boiler is reduced by 19.1% and the boiler efficiency increases from 92.7% to 95.4%. The impacts of the water content of the dried coal and the unit heating capacity on the energy-saving effect of the new concept were also examined.

Thermodynamic and Performance Study of Solar Regenerative Organic Rankine Cycle System for Use in Residential Micro-Combined Heat and Power Generation

2019 ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev
Keyword(s):  
Power Generation ◽  
Energy Demand ◽  
Waste Heat ◽  
Residential Buildings ◽  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Heat And Power ◽  
Energy Sources ◽  
Performance Study

Abstract A continued increase in both energy demand and greenhouse gas emissions (GHGs) call for utilising energy sources effectively. In comparison with traditional energy set-ups, micro-combined heat and power (micro-CHP) generation is viewed as an effective alternative; the aforementioned system’s definite electrical and thermal generation may be attributed to an augmented energy efficiency, decreased capacity as well as GHGs percentage. In this regard, organic Rankine cycle (ORC) has gained increasing recognition as a system, which is capable for generating electrical power from solar-based, waste heat, or thermal energy sources of a lower quality, for instance, below 120 °C. This study focuses on investigating a solar-based micro-CHP system’s performance for use in residential buildings through utilising a regenerative ORC. The analysis will focus on modelling and simulation as well as optimisation of operating condition of several working fluids (WFs) in ORC in order to use a heat source with low-temperature derived from solar thermal collectors for both heat and power generation. A parametric study has been carried out in detail for analysing the effects of different WFs at varying temperatures and flowrates from hot and cold sources on system performance. Significant changes were revealed in the study’s outcomes regarding performance including efficiency as well as power obtained from the expander and generator, taking into account the different temperatures of hot and cold sources for each WF. Work extraction carried out by the expander and electrical power had a range suitable for residential building applications; this range was 0.5–5 kWe with up to 60% electrical isentropic efficiency and up to 8% cycle efficiency for 50–120 °C temperature from a hot source. The operation of WFs will occur in the hot source temperature range, allowing the usage of either solar flat plate or evacuated tube collectors.

Targeting and design of industrial zone waste heat reuse for combined heat and power generation

Energy ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 302-313 ◽  
Author(s):  
Vladimir Z. Stijepovic ◽  
Patrick Linke ◽  
Mirko Z. Stijepovic ◽  
Mirjana Lj. Kijevčanin ◽  
Slobodan Šerbanović
Keyword(s):  
Power Generation ◽  
Waste Heat ◽  
Combined Heat And Power ◽  
Industrial Zone ◽  
Waste Heat Reuse

Evaluation of Combined Heat and Power (CHP) Systems Performance With Dual Power Generation Units

2012 ◽  
Author(s):  
Alta Knizley ◽  
Pedro J. Mago
Keyword(s):  
Power Generation ◽  
Carbon Dioxide Emissions ◽  
Operating Cost ◽  
Primary Energy ◽  
Combined Heat And Power ◽  
Department Of Energy ◽  
Environmental Benefits ◽  
Optimum Operating ◽  
Electric Load ◽  
Chp System

This paper evaluates the economic, energetic, and environmental feasibility of using two power generation units (PGUs) to operate a combined heat and power (CHP) system. A benchmark building developed by the Department of Energy for a full-service restaurant in Chicago, IL is used to analyze the proposed configuration. This location is selected since it usually provides favorable CHP system conditions in terms of cost and emissions reduction. In this investigation, one PGU is operated at base load to satisfy part of the electricity building requirements (PGU1), while the other is used to satisfy the remaining electricity requirement operating following the electric load (PGU2). The dual-PGU configuration (D-CHP) is modeled for several different scenarios in order to determine the optimum operating range for the selected benchmark building. The dual-PGU scenario is compared with the reference building using conventional technology to determine the economical, energetic, and environmental benefits of this proposed system. This condition is also compared to a CHP system operating following the electric load (FEL) and to a base-loaded CHP system, and it provides greater savings in operating cost, primary energy consumption, and carbon dioxide emissions than the optimized conditions for base loading and FEL.

scholarly journals Addressing Industrial Waste Heat Supply Variability With Organic Rankine Cycle Systems Incorporating Thermal Energy Storage

2021 ◽  
Author(s):  
Bipul Krishna Saha ◽  
Basab Chakraborty ◽  
Rohan Dutta
Keyword(s):  
Power Generation ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade

Abstract Industrial low-grade waste heat is lost, wasted and deposited in the atmosphere and is not put to any practical use. Different technologies are available to enable waste heat recovery, which can enhance system energy efficiency and reduce total energy consumption. Power plants are energy-intensive plants with low-grade waste heat. In the case of such plants, recovery of low-grade waste heat is gaining considerable interest. However, in such plants, power generation often varies based on market demand. Such variations may adversely influence any recovery system's performance and the economy, including the Organic Rankine Cycle (ORC). ORC technologies coupled with Cryogenic Energy Storage (CES) may be used for power generation by utilizing the waste heat from such power plants. The heat of compression in a CES may be stored in thermal energy storage systems and utilized in ORC or Regenerative ORC (RORC) for power generation during the system's discharge cycle. This may compensate for the variation of the waste heat from the power plant, and thereby, the ORC system may always work under-designed capacity. This paper presents the thermo-economic analysis of such an ORC system. In the analysis, a steady-state simulation of the ORC system has been developed in a commercial process simulator after validating the results with experimental data for a typical coke-oven plant. Forty-nine different working fluids were evaluated for power generation parameters, first law efficiencies, purchase equipment cost, and fixed investment payback period to identify the best working fluid.

New Technologies

Energy ◽  
2012 ◽  
Author(s):  
José Goldemberg
Keyword(s):  
Power Plant ◽  
Thermal Energy ◽  
Thermal Power Plant ◽  
New Technologies ◽  
Waste Heat ◽  
Thermal Power ◽  
Energy Systems ◽  
Combined Heat And Power ◽  
Simultaneous Production ◽  
Burning Coal

What is cogeneration? Cogeneration or CHP (combined heat and power) devices allow the simultaneous production of electric and thermal energy in energy systems. They typically recover and use waste heat from a thermal power plant burning coal. These systems are widely used in Eastern...

Evaluation of Energy, Environmental, and Economic Characteristics of Fuel Cell Combined Heat and Power Systems for Residential Applications

2003 ◽  
Vol 125 (3) ◽  
pp. 208-220 ◽  
Author(s):  
M. Burak Gunes ◽  
Michael W. Ellis
Keyword(s):  
Life Cycle ◽  
Fuel Cell ◽  
Thermal Energy ◽  
Life Cycle Cost ◽  
Energy Use ◽  
Combined Heat And Power ◽  
Environmental Benefits ◽  
Design Parameters ◽  
Single Family ◽  
Chp System

Residential combined heat and power (CHP) systems using fuel cell technology can provide both electricity and heat and can substantially reduce the energy and environmental impact associated with residential applications. The energy, environmental, and economic characteristics of fuel cell CHP systems are investigated for single-family residential applications. Hourly energy use profiles for electricity and thermal energy are determined for typical residential applications. A mathematical model of a residential fuel cell based CHP system is developed. The CHP system incorporates a fuel cell system to supply electricity and thermal energy, a vapor compression heat pump to provide cooling in the summer and heating in the winter, and a thermal storage tank to help match the available thermal energy to the thermal energy needs. The performance of the system is evaluated for different climates. Results from the study include an evaluation of the major design parameters of the system, load duration curves, an evaluation of the effect of climate on energy use characteristics, an assessment of the reduction in emissions, and a comparison of the life cycle cost of the fuel cell based CHP system to the life cycle costs of conventional residential energy systems. The results suggest that the fuel cell CHP system provides substantial energy and environmental benefits but that the cost of the fuel cell sub-system must be reduced to roughly $500/kWe before the system can be economically justified.

Thermodynamic Analysis of Sintering Waste Heat Power Generation

2011 ◽  
Vol 71-78 ◽  
pp. 2562-2565
Author(s):  
Tao Du ◽  
Jian Bo Yang ◽  
Hong Lin Zhang
Keyword(s):  
Heat Transfer ◽  
Power Generation ◽  
Thermodynamic Analysis ◽  
Heat Generation ◽  
Waste Heat ◽  
Generation Process ◽  
Regenerative Heat ◽  
Waste Heat Utilization ◽  
Cooling Air ◽  
The Heat Balance

The current domestic conditions of sintering waste heat generation are introduced. The waste heat utilization methods are given according to waste heat characteristics of 360m2 sintering machine. The particle regenerative heat exchanger model is used to calculate heat transfer area of the first part of the circular-cooler. The logarithmic mean temperature difference method is used to calculate the heat transfer of closed cycle cooling air and the temperature of exhaust gas. The thermodynamic analysis of sintering heat generation process is completed. The power generation efficiency and quantity are calculated by using the heat balance and exergy analysis method.

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