Application of an Advanced Simulation Model to a Micro-CHP ORC-Based System for Ultra-Low Grade Heat Recovery

2012 ◽  
Author(s):  
Davide Ziviani ◽  
Asfaw Beyene ◽  
Mauro Venturini
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
Heat Recovery ◽  
Residential Building ◽  
Hot Water ◽  
Low Grade ◽  
Solar Thermal Energy ◽  
Working Medium ◽  
Cooling Loads ◽  
Low Grade Heat

This paper presents the results of the application of an advanced thermodynamic model developed by the authors for the simulation of Organic Rankine Cycles (ORCs). The model allows ORC simulation both for steady and transient analysis. The expander, selected to be a scroll expander, is modeled in detail by decomposing the behavior of the fluid stream into several steps. The heat source is coupled with the system through a plate heat exchanger, which is modeled using an iterative sub-heat exchanger modeling approach. The considered ORC system uses solar thermal energy for ultra-low grade heat recovery. The simulation model is used to investigate the influence of ORC characteristic parameters related to the working medium, hot reservoir and component efficiencies for the purpose of optimizing the ORC system efficiency and power output. Moreover, dynamic response of the ORC is also evaluated for two scenarios, i.e. (i) supplying electricity for a typical residential user and (ii) being driven by a hot reservoir. Finally, the simulation model is used to evaluate ORC capability to meet electric, thermal and cooling loads of a single residential building, for typical temperatures of the hot water exiting from a solar collector.

Design, Analysis and Optimization of a Micro-CHP System Based on Organic Rankine Cycle for Ultralow Grade Thermal Energy Recovery

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Davide Ziviani ◽  
Asfaw Beyene ◽  
Mauro Venturini
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
Thermal Energy ◽  
Energy Recovery ◽  
Organic Rankine Cycle ◽  
Residential Building ◽  
Rankine Cycle ◽  
Hot Water ◽  
Solar Thermal Energy ◽  
Chp System

This paper presents the results of the application of an advanced thermodynamic model developed by the authors for the simulation of Organic Rankine Cycles (ORCs). The model allows ORC simulation both for steady and transient analysis. The expander, selected to be a scroll expander, is modeled in detail by decomposing the behavior of the fluid stream into several steps. The energy source is coupled with the system through a plate heat exchanger (PHE), which is modeled using an iterative sub-heat exchanger modeling approach. The considered ORC system uses solar thermal energy for ultralow grade thermal energy recovery. The simulation model is used to investigate the influence of ORC characteristic parameters related to the working medium, hot reservoir and component efficiencies for the purpose of optimizing the ORC system efficiency and power output. Moreover, dynamic response of the ORC is also evaluated for two scenarios, i.e. (i) supplying electricity for a typical residential user and (ii) being driven by a hot reservoir. Finally, the simulation model is used to evaluate ORC capability to meet electric, thermal and cooling loads of a single residential building, for typical temperatures of the hot water exiting from a solar collector.

Development and Validation of an Advanced Simulation Model for ORC-Based Systems

2012 ◽  
Author(s):  
Davide Ziviani ◽  
Asfaw Beyene ◽  
Mauro Venturini
Keyword(s):  
Heat Exchanger ◽  
Simulation Model ◽  
System Modeling ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Low Grade ◽  
Key Characteristics ◽  
Low Grade Heat ◽  
Development And Validation ◽  
Power Generation Systems

Low-grade heat recovery from solar or geothermal energy may be an eco-friendly resource for electric and thermal energy recovery. The Organic Rankine Cycle (ORC) is one of the main candidates to exploit low-temperature heat sources, otherwise difficult to access using conventional power generation systems. In this paper, an advanced thermodynamic model of an ORC is developed, with the final aim to optimize ORC conversion efficiency, especially for micro-CHP applications. First, a thorough review of issues related to ORC system modeling is presented by analyzing the state-of-the-art experience and advancements. Subsequently, an advanced simulation model is developed, by taking advantage of all the key characteristics of the models presented in the literature. The simulation model is developed in Matlab®/AMESim® environment, which allows system modeling both for steady and transient analysis. The heat source is coupled with the system through a plate heat exchanger, which is modeled using an iterative sub-heat exchanger modeling approach. A scroll expander, modeled in detail by decomposing the behavior of the fluid stream into several steps, is used to extract the useful work. Finally, model predictions for the evaporator and the expander are validated against both numerical and experimental data published in literature. The simulation model of the entire ORC system is also validated against literature data taken on a test bench.

Feasibility Study of Low Grade Heat Recovery Rankine Cycle Using Ozone-Neutral Refrigerant

2008 ◽  
Author(s):  
W. Wayne Husband ◽  
Asfaw Beyene
Keyword(s):  
Heat Recovery ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Rankine Cycle ◽  
Theoretical Models ◽  
Photovoltaic System ◽  
Working Fluid ◽  
Low Grade ◽  
Management Tools ◽  
Low Grade Heat

The paper addresses the feasibility of ozone-neutral low grade heat recovery to produce power. The low grade heat source can either be industrial exhaust or solar radiation. Using a scroll expander as a basis for testing, theoretical models yielded a thermal efficiency of 11%, utilizing a non-toxic and non-hazardous working fluid. This project spanned research and development of a system from the comparison of several working fluids, modeling of a theoretical 10 kW unit, the sizing and selection of appropriate system components, and the development of project management tools, in support of its real world development. A cost benefit analysis of the theoretical system shows that solar heat recovery with ozone-neutral refrigerant is a viable option for power generation, at about 1/3 the cost of a comparable photovoltaic system.

Analytical and Experimental Study of Potential Heat Recovery From Household Refrigerators

2004 ◽  
Author(s):  
Jessica Todd
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat ◽  
Tap Water ◽  
Economic Feasibility ◽  
Hot Water ◽  
Coil Design ◽  
Waste Heat Recovery System ◽  
Recovery Potential

Opportunities for waste recovery exist in many types of industrial devices as summarized by Kreith and West [1]. However, no experimental data regarding the potential of heat recovery from household refrigerators have been published in open literature. The decision to implement a heat recovery option depends mostly on convenience and cost. In some cases, however, the decision is difficult because there is a lack of reliable information of the payback for a potential application. This article provides useful information for the design and payback of a waste heat recovery system on a household refrigerator. This paper presents experimental and analytical results of energy recovery potential from the heat rejected by the condenser coils of a household refrigerator. Using a small heat exchanger affixed to the condenser coils, the heat thus recovered can preheat domestic tap water. The analytical study considered three designs: A heat exchanger with the refrigerant condensing on the outside of water pipes, refrigerant on the inside of a counter-flow heat exchanger, and the refrigerant condensing inside a serpentine coil enclosed by a container filled with household tap water. Considering economic feasibility and manufacturing ease, the serpentine coil design was chosen. Experimental data confirmed the heat recovery possibility from the condenser coils. The serpentine coil design can achieve a payback time of 2 to 10 years dependent on whether the domestic hot water uses electric or gas heating.

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