Working Fluid Selection and Technoeconomic Optimization of a Turbocompression Cooling System

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Derek Young ◽  
Spencer C. Gibson ◽  
Todd M. Bandhauer
Keyword(s):  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cooling System ◽  
Payback Period ◽  
Working Fluid ◽  
Low Grade ◽  
Diesel Generator ◽  
Working Fluids

Abstract Low grade waste heat recovery presents an opportunity to utilize typically wasted energy to reduce overall energy consumption and improve system efficiencies. In this work, the technoeconomic performance of a turbocompression cooling system (TCCS) driven by low grade waste heat in the engine coolant of a large marine diesel generator set is investigated. Five different working fluids were examined to better understand the effects of fluid characteristics on system performance: R134a, R245fa, R1234ze(E), R152a, and R600a. A coupled thermodynamic, heat exchanger, and economic simulation was developed to calculate the simple payback period of the waste heat recovery system, which was minimized using a search and find optimization routine with heat exchanger effectiveness as the optimization parameter. A sensitivity study was performed to understand which heat exchanger effectiveness had the largest impact on payback period. Of the five working fluids examined, a TCCS with R152a as the working fluid had the lowest payback period of 1.46 years with an initial investment of $181,846. The R152a system was most sensitive to the two-phase region of the power cycle condenser. The R1234ze(E) system provided the largest return on investment over a ten year lifetime of $1,399,666.

scholarly journals Design and Operational Control Strategy for Optimum Off-Design Performance of an ORC Plant for Low-Grade Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5846
Author(s):  
Fabio Fatigati ◽  
Diego Vittorini ◽  
Yaxiong Wang ◽  
Jian Song ◽  
Christos N. Markides ◽  
...  
Keyword(s):  
Power Unit ◽  
Control Strategy ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Combustion Engine ◽  
Working Fluid ◽  
Thermal Source ◽  
Low Grade ◽  
Gear Pump

The applicability of organic Rankine cycle (ORC) technology to waste heat recovery (WHR) is currently experiencing growing interest and accelerated technological development. The utilization of low-to-medium grade thermal energy sources, especially in the presence of heat source intermittency in applications where the thermal source is characterized by highly variable thermodynamic conditions, requires a control strategy for off-design operation to achieve optimal ORC power-unit performance. This paper presents a validated comprehensive model for off-design analysis of an ORC power-unit, with R236fa as the working fluid, a gear pump, and a 1.5 kW sliding vane rotary expander (SVRE) for WHR from the exhaust gases of a light-duty internal combustion engine. Model validation is performed using data from an extensive experimental campaign on both the rotary equipment (pump, expander) and the remainder components of the plant, namely the heat recovery vapor generator (HRVH), condenser, reservoirs, and piping. Based on the validated computational platform, the benefits on the ORC plant net power output and efficiency of either a variable permeability expander or of sliding vane rotary pump optimization are assessed. The novelty introduced by this optimization strategy is that the evaluations are conducted by a numerical model, which reproduces the real features of the ORC plant. This approach ensures an analysis of the whole system both from a plant and cycle point of view, catching some real aspects that are otherwise undetectable. These optimization strategies are considered as a baseline ORC plant that suffers low expander efficiency (30%) and a large parasitic pumping power, with a backwork ratio (BWR) of up to 60%. It is found that the benefits on the expander power arising from a lower permeability combined with a lower energy demand by the pump (20% of BWR) for circulation of the working fluid allows a better recovery performance for the ORC plant with respect to the baseline case. Adopting the optimization strategies, the average efficiency and maximum generated power increase from 1.5% to 3.5% and from 400 to 1100 W, respectively. These performances are in accordance with the plant efficiencies found in the experimental works in the literature, which vary between 1.6% and 6.5% for similar applications. Nonetheless, there is still room for improvement regarding a proper design of rotary machines, which can be redesigned considering the indications resulting from the developed optimization analysis.

Design and Optimization of Waste Heat Recovery Unit Using Carbon Dioxide as Cooling Fluid

2014 ◽  
Author(s):  
Geir Skaugen ◽  
Harald T. Walnum ◽  
Brede A. L. Hagen ◽  
Daniel P. Clos ◽  
Marit J. Mazzetti ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Working Fluid ◽  
Design And Optimization ◽  
Power Cycle ◽  
Turbine Efficiency ◽  
Recovery Unit ◽  
Process Simulations

This paper describes design and optimization of a Waste Heat Recovery Unit (WHRU) for a power cycle which uses CO2 as a working fluid. This system is designed for offshore installation to increase gas turbine efficiency by recovering waste heat from the exhaust for production of additional power. Due to severe constraints on weight and space in an offshore setting, it is essential to reduce size and weight of the equipment to a minimum. Process simulations are performed to optimize the geometry of the WHRU using different objective functions and thermal-hydraulic models. The underlying heat exchanger model used in the simulations is an in-house model that includes the calculation of weight and volume for frame and structure for the casing in addition to the thermal-hydraulic performance of the heat exchanger core. The results show that the for a set of given process constraints, optimization with respect to minimum total weight or minimum core weight shown similar results for the total installed weight, although the design of heat exchanger differs. The applied method also shows how the WHRU geometry can be optimized for different material combinations.

Oscillating Heat Pipes for Waste Heat Recovery in HVAC Systems

2015 ◽  
Author(s):  
Govinda Mahajan ◽  
Heejin Cho ◽  
Scott M. Thompson ◽  
Harrison Rupp ◽  
Kevin Muse
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Pipes ◽  
Hvac Systems ◽  
Operating Conditions ◽  
Working Fluid ◽  
Low Grade ◽  
Potential Cost

Oscillating heat pipes (OHPs) were experimentally assessed as a passive-type heat transfer device for air-to-air heat exchange in a typical Heating Ventilation & Air conditioning system (HVAC) with adjacent air streams at different temperatures. The objective is to utilize, otherwise wasted thermal energy to pre-heat or pre-cool air in order to reduce the payload on HVAC systems, thus reducing energy consumption. OHPs can achieve effective thermal conductivities on-the-order of 10,000 W/m-K via no internal wicking structure and hence can perform aforementioned heat transfer task while providing an aerodynamic form factor. A unique working fluid with limited research inside OHPs, but with properties desirable for low grade heat fluxes, i.e. n-pentane with 70 % fill ratio, was chosen as the working fluid to achieve maximum heat transfer. Aerodynamic performance, in terms of pressure drop, was evaluated and juxtaposed with heat transfer gain/loss. The OHP thermal performance and total heat transfer for hot-environment HVAC operation was benchmarked with an empty/evacuated OHP with same overall dimensions. Results indicate that the current, atypically-long OHP is fully-capable of operating in the air-to-air convection mode for waste heat recovery for typical HVAC operating conditions. Since the OHP is passive, cost effective, and relatively aerodynamic (no fins were used), the potential cost savings for its integration into HVAC systems can be significant.

scholarly journals Comparison between Organic Working Fluids in order to Improve Waste Heat Recovery from Internal Combustion Engines by means of Rankine Cycle Systems

2020 ◽  
Vol 71 (1) ◽  
pp. 113-121
Author(s):  
Alexandru Racovitza ◽  
Horatiu Pop ◽  
Valentin Apostol ◽  
Tudor Prisecaru ◽  
Daniel Taban
Keyword(s):  
Thermal Efficiency ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Internal Combustion Engines ◽  
Waste Heat ◽  
Rankine Cycle ◽  
Internal Combustion ◽  
Working Fluid ◽  
Working Fluids ◽  
Cycle Systems

The present works deals with waste heat recovery from internal combustion engines using Rankine cycle systems where working fluid are organic liquids (ORC). The first part of the paper presents the ORC technology as one of the most suitable procedure for waste heat recovery from exhaust gas of internal combustion engine (ICE). The particular engine considered in the present work is a turbocharged compression ignition engine mounted on an experimental setup. The working fluids for ORC system are: isobutene, propane, RE245fa2, RE245cb2, R245fa, R236fa, R365mfc, R1233zd(E), R1234yf and R1234ze(Z). Experimental data derived from the experimental setup has been used for 40%, 55% and 70% engine load. This papers focusses on superheating increment, on thermal efficiency and on net power output, obtained with each working fluids in Rankine cycle. Results point out the superheating increment that gives the highest thermal efficiency for each working fluid. The highest thermal efficiency is achieved in case of using R1233zd(E) as working fluid. In case of using R1233zd(E) as working fluid at 40 % load of the engine, the output power of the Rankine cycle is 3.6 kW representing 6.2 %, from the rated power at this load; at 55% load it is 5.7 kW representing 6.7 % the rated power and at 70% it is 6.7 kW representing 6.5 % from the rated power. Future perspectives are given.

Design of an Organic Rankine Cycle for Waste Heat Recovery From a Portable Diesel Generator

2011 ◽  
Author(s):  
Frederick J. Cogswell ◽  
David W. Gerlach ◽  
Timothy C. Wagner ◽  
Jarso Mulugeta
Keyword(s):  
Power Generation ◽  
Heat Exchanger ◽  
Heat Recovery ◽  
High Speed ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Diesel Generator ◽  
Air Conditioners

A 5-kW Organic Rankine Cycle (ORC) was designed for mobile 60-kW diesel engine waste heat recovery applications to provide additional electricity for powering air conditioners. The ORC uses a non-flammable, near-zero-global-warming-potential fluid (Novec649) in a supercritical cycle. The system conceptual design and some observations on the component specification are described. The system will utilize an advanced oil-free high speed direct drive turbine. The proposed power generation module has a volume of ∼3 ft3 and contains the turbine, generator, pump, recuperator, and electrical components. The heat rejection heat exchanger is located on the power generation module in a configuration similar to mini-split air conditioners. The heat recovery heat exchanger (supercritical heater) is attached to the diesel generator and placed in series before the OEM muffler. The supercritical heater must be carefully designed to prevent the refrigerant from overheating, while still maintaining a high effectiveness.

Economic Feasibility Study of a Small Scale Organic Rankine Cycle System in Waste Heat Recovery Application

2010 ◽  
Author(s):  
Bertrand F. Tchanche ◽  
Sylvain Quoilin ◽  
Sebastien Declaye ◽  
Georges Papadakis ◽  
Vincent Lemort
Keyword(s):  
Thermodynamic Model ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Payback Period ◽  
Working Fluid ◽  
Small Scale ◽  
Electricity Cost

The Organic Rankine Cycle (ORC) appears progressively as a promising solution to recover waste heat energy from thermal processes for electricity generation. A prototype of small-scale ORC has been built and successfully tested at the University of Lie`ge. It uses R-245fa and R-123 as working fluid, and an oil-free scroll compressor adapted to run in expander mode. Thermodynamic model of the system was derived and validated for performance prediction. The validated thermodynamic model is used to optimize the operation of the small ORC in waste heat recovery application (ORC-WHR). For exhaust gases at 180 °C and a mass flow rate of 0.21 kg/s, a maximum net power output of 2 kWe is obtained for an evaporator pressure of 11.84 bar. The cycle thermal efficiency is 8.23 and the recuperation efficiency, 66.32%. Based on the aforementioned conditions, the economic assessment of small scale ORC-WHR was carried out using economic criteria such as levelized electricity cost (LEC), Net present value (NPV) and depreciated payback period (DPP). For a 2kWe ORC-WHR, the specific installed cost is 5775 €/kW with a LEC of 13.27 c€/kWh while for a 50 kWe, the specific installed cost is about 3034 €/kW and the LEC, 7c€/kWh. For an electricity unit price of 20 c€/kWh, the payback period of a 2 kWe system is 6 years while it is 2.5 years for a 50 kWe system. It is concluded from the study that recovering the waste heat by way of ORCs is technically and economically feasible. As recycled energy, waste heat has the same advantages as renewable energy and should benefit from the same legislative conditions (Feed-in-Laws).

Sign in / Sign up

Export Citation Format

Share Document