Grant Award Year: 2017-2018
Principal Investigator:
Jon McGowan, Mechanical and Industrial Engineering,University of Massachusetts Amherst
Research Description:
To develop a conceptual model for a solar hybrid energy-desalination system capable of producing fresh water and electricity.
Report
Basic Information
- Project Number: 2017MA463B
- Start Date: 3/1/2017
- End Date: 2/28/2018
- Funding Source: 104B
- Congressional District: MA-002
- Research Category: Engineering
- Focus Categories: Water Supply, Water Quantity, Models
- Descriptors: None
- Principal Investigators: Jon McGowan, Matthew Arenson Lackner
Publications
- Mohammadi,Kasra; Jon G. McGowan, 2018, Thermodynamic analysis of hybrid cycles based on a regenerative steam Rankine cycle for cogeneration and trigeneration, Energy Conversion and Management, 158, 460–475.
- Mohammadi,Kasra; Jon G. McGowan, Under Review, A thermo-economic analysis of a combined cooling system for air conditioning and low to medium temperature refrigeration, Journal of Cleaner Production, Elsevier.
- Mohammadi,Kasra; Jon G. McGowan, Under Review, An efficient integrated trigeneration system for productions of dual temperature cooling and fresh water: thermoeconomic analysis and optimization, Applied Thermal Engineering, Elsevier.
- Mohammadi, Kasra, 2018, Thermo-economic and optimization of several hybrid multigeneration systems driven by concentrated solar tower plants, PhD Dissertation, Mechanical Engineering Deparmtent, University of Massachusetts Amherst, Amherst, Massachusetts, pp. TBA
Problem and Research Objectives
In recent decades, growth in the world population, economic and living standards have been responsible for substantial increases in global energy consumption. Moreover, exploitation of fossil fuels to supply energy demands has led to global climate change, which is expected to have far-reaching and longlasting consequences on the planet. These factors have motivated the importance and necessity of developing more efficient ways for energy conservation and generation that avoid the production of greenhouse gases that contribute to climate change. One method to address these issues is to develop combined production such as cogeneration, trigeneration, and multigeneration for simultaneous production of electricity, cooling, heating, fresh water, etc. using renewable energy sources such as solar. By using hybrid systems with multiple output products, the overall efficiency of the system can be increased over a single output system, and by using renewable sources, carbon and other harmful emissions are avoided.
The overall objective of this project is to propose, model, simulate, and optimize several integrated systems that can efficiently, renewably, sustainably, and economically address different demands including power, fresh water, cooling, and heating for both residential and industrial applications. Concentrated solar tower is used as a prime or supplementary mover for all proposed configurations and cycles, enabling a high temperature thermal heat source to generate electricity and provide thermal requirements of other systems.
Concentrated solar tower technology has attracted more interest in recent years due to its capability to provide high temperature thermal energy leading to a higher thermodynamic efficiency. Several solar tower technologies have been proposed that employ different design receivers and utilize different heat transfer fluids including molten salt, air, water/steam, CO2, liquid metals and solid particles. In this project, however, the main focus is on utilizing air and CO2 as working fluid in the solar receiver.
A main common aspect of all solar tower technologies is the utilization of several mirrors (heliostats) to reflect and concentrate direct normal irradiation (DNI) to a receiver mounted on the top of a tower. The heliostat field performance is described based on the optical efficiency, which is the ratio of the net energy reflected by heliostat field and absorbed by the receiver to the incident energy on the heliostat field.
A significant part of the required investment cost for developing solar tower technologies is attributed to heliostat field. Therefore, optimal design of heliostat field is of high significance to improve the optical efficiency of the field and overall performance of the system and reduce the investment cost.
This project differs from previous investigations and brings new contributions to the research community in several different key aspects. The novelty of this research mainly lies in the development of several novel utility scales cogeneration, trigeneration and multigeneration configurations using the above sub-systems that satisfy the most important demands in both the residential sector as well as industrial sector such as food, textile, chemical, oil, etc. Also, an efficient multi-objective optimization approach will be employed to introduce the most suitable configurations for each sector to reach higher profitability of the plant, higher efficiency, reliability and sustainability of the system as well as lower environmental impacts. Furthermore, another novel aspect of the project is the development of control schemes and strategies that can meet all the operational, reliability and safety requirements of the hybrid system operating autonomously throughout the year. This makes the developed hybrid system and mathematical model realistic and applicable for both sectors for year-round utilization. Finally, a number of case studies in the United States and worldwide will be developed and the optimization process and control scheme will be developed based on the possible electricity, fresh water, cooling and heating demands of each case study.
One of the important aspects to integrate power cycles with other cycles such as cooling, heating, and desalination for trigeneration and multigeneration purposes, is that integration should be accomplished in such a way that it minimizes the impact on the power production. This consideration is relevant for all configurations and systems in this project.
The objectives of this project include:
- Specific objective 1: Create several computational codes that can simulate different integrated system based on the concentrated solar tower as a prime mover for the purpose of multigeneration of electricity, fresh water, cooling and heating. The integration of concentrated solar tower to the hightemperature, high-efficiency power cycles such as a Rankine or Brayton combined cycle is modeled. By using a combined cycle, a system is modeled that can reach higher operating temperatures and produce more electricity than the case of the Rankine cycle.
- Specific objective 2: Propose and evaluate different thermodynamic configurations using the above mentioned sub-systems that can be applied to the residential and industrial sectors. For this aim, the developed computational codes simulate utility scale multigeneration systems at different scales. Then the plant economic performance is assessed by performing a detailed economic evaluation in terms of cost analysis, payback period and other important economic factors. In economic evaluation, the variation of cost is investigated due to modifications in the plant configuration, especially high temperature cycles, desalination units and refrigeration systems.
- Specific objective 3: Via sensitivity analyses, determine and introduce the most important design parameters that influence the performance and economic of each proposed integrated configuration.
- Specific objective 4: Apply an efficient multi-objective optimization approach to optimize each proposed configuration and introduce the most suitable configurations. The optimization approach enables a trade-off between higher performance, lower capital investment as well as the cost of generation of electricity, fresh water, cooling and heating, environmental concerns and sustainability.
- Specific objective 5: Compare the performance of optimized hybrid systems with separate plants that do not implement a hybrid approach, cogeneration plants (producing two useful outputs) and trigeneration plants (producing three useful outputs).
Specific objective 6: Consider several case studies in the United States, as well as other parts of the world, with different energy, fresh water, cooling and heating demands in both residential and industrial sectors as well as different climate conditions and solar energy features. Site-specific direct normal irradiation (DNI) data and other required climate data are collected and used in simulations.
The results generated from this project will provide substantial insight regarding the technical, economic and environmental aspects of utility scale hybrid multigeneration systems using concentrated solar tower as a primary or supplementary energy source. The proposed configurations have the potential to make a significant impact on supplying all products. This project will provide guidelines for constructors, investors, decision makers and plant operators with a large number of decisions including choosing the optimal configurations based on existing demands of a location as well as operating and controlling the sub-systems.
Methodology
To fulfill the objectives, several computational codes are developed using engineering equation solver (EES) software. EES is an equation-solving program that enables the solution of thousands of non-linear equations numerically. One of the main features of EES that significantly assists this research is its high accuracy thermodynamic and transport property databases for hundreds of substances, enabling it to simulate thermodynamic cycles that use different fluids [24]. The computational codes to simulate hybrid systems in this project include any of the following advanced systems:
- Concentrated solar tower systems as a primary or supplementary mover
- Back-up energy using natural gas
- High efficiency steam and transcritical CO2 Rankine power cycles
- High efficiency Brayton and combined power cycles
- High efficiency supercritical CO2 Brayton power cycles
- Organic Rankine cycle (ORC) power cycles
- A thermally driven MED or TVC-MED water desalination system
- Thermally driven LiBr-H2O absorption cooling cycles
- Thermally driven NH3-H2O absorption refrigeration cycles
- An electrically driven vapor compression or cascade refrigeration cycle
For all above-mentioned advanced cycles, proper thermodynamic models were developed and implemented in EES. The thermodynamic mathematical modeling of all cycles was carried out under steady state and steady flow (SSSF) conditions by assuming negligible kinetic, potential and chemical energies.
For an economic evaluation of the proposed integrated systems, economic models were developed to calculate different economic indicators such as total annual cost (TAC), annual capital cost (ACC), annual operating cost (AOC), levelized cost of energy (LCOE), levelized cost of cooling (LCOC), levelized cost of water (LCOW), net present value (NPV) and payback period (PBP).
As noted, due to the significant capital cost of heliostat field (mirrors), optimal design of heliostat field is of high significance to improve the optical efficiency of the field and overall performance of the system and reduce the investment cost. For this purpose, a detailed mathematical modeling is developed using Matlab to simulate the performance of different sizes heliostat field and provide an optimal filed configuration to achieve a higher flied efficiency and a lower capital cost.
Principal Findings and Significance
The developed computational tools can simulate the operation of proposed integrated systems at various operating conditions and at different geographical locations. They enable parametric studies to identify the influence of several design parameters on the overall performance of systems. The developed computational codes for all considered cycles allow evaluation of several feasible configurations for different residential and industrial applications. Using the developed computational codes, it is also possible to conduct component and system configuration optimization to achieve optimal production of electricity, fresh water, heating and cooling.
The important contribution of this research is the proposal of different new integrated systems. The proposed systems can be developed and implemented for practical applications to supply the demands efficiently and economically in both residential and industrial sectors. Techno-economic analysis of the proposed hybrid systems for efficient energy utilization is a creative contribution to the body of knowledge.
The results of this research demonstrate that proposed multigeneration systems can supply multiple demands including electricity, fresh water and cooling at a higher thermodynamic efficiency and lower capital and operating costs than single production of these multiple useful products.