Design Of Waste Heat Recovery System Research Articles

Load characteristics analysis of the water source heat pump heating system using data center waste heat

The number and scale of data centers (DCs) in China are constantly expanding with the advancement of networking and informatization. A large amount of waste heat is dissipated at its end. If this waste heat can be recovered, then achieving carbon neutrality in DCs can be effectively accelerated. At present, water source heat pump (WSHP) are widely used in air-cooled and liquid-cooled DCs of different sizes for waste heat recovery. This study analyzes the equipment type and heating capacity of different brands of WSHP units. Three WSHP heating systems are proposed according to the different locations of waste heat enhancement (SE, TDE, UE). The coupling and matching relationship between user-side heat load demand, DC waste heat load, and energy efficiency of WSHP units under different systems is also investigated. Moreover, the law of energy consumption and energy efficiency changes is analyzed. Thus, this study provides a reference for the DC waste heat recovery system design and equipment development. The results show that the coupling matching relationship between user-side heat load demand, DC waste heat load, and heating COP of WSHP units is Q.N/Q.S=COP′/COP′-1=φ, where φ ranges from 1.1962 to 1.3642. The heating COP of the SE system is the greatest when user-side heat load demand is between 0 and 120 kW. The heating COP of the TDE system is the highest when the user-side heat load demand is between 1750 and 70000 kW. Furthermore, the heating COP of the three WSHP heating system types is related to unit brand when user-side heat load demand is between 120 and 1750 kW.

Integrated Heat Regenerator (IHR) Designs with Hydrogen Preheater and Thermoelectric Generator for Power Enhancement of a 2 kW Fuel Cell Vehicle

The power train efficiency of fuel cell vehicles (FCV) can be enhanced by improving the hydrogen energy utilization. Based on a mini FCV running on a 2 kW open-cathode Polymer Electrolyte Membrane (PEM) fuel cell, a waste heat recovery system design needs to be developed as an approach towards higher energy efficiency. The novelty of the system is on the integration of thermoelectric generator technology with hydrogen preheating process for a combined heat and power output. This manuscript presents the proposed integrated heat regenerator (IHR) designs, analysed using numerical computational modelling. Three IHR designs were proposed where the main design criteria are (i) a minimum of 10oC hydrogen preheating degree, and (ii) non-parasitic active cooling for the Thermoelectric generator (TEG) cells. Three design concepts were studied to identify its design and performance limitations. The numerical results were validated with theoretical modelling analysis for hydrogen exit temperatures and TEG surface temperatures. The analysis on predicted fuel cell power enhancement, TEG power generation and waste heat utilization were performed by relating the temperature profiles of the hydrogen reactant and TEG surfaces to fuel cell reaction models and TEG power relationships. A compact IHR design that produced 7.7 to 8 % total power enhancement and suitable in size for a mini FCV was identified for future development works

EXERGY BASED SUSTAINABILITY ASSESSMENT OF AN ORC INTEGRATED WASTE HEAT RECOVERY SYSTEM FOR MARINE VESSELS

This paper introduces the basics of exergy based sustainability assessment and the framework that should be shaped within in the first stage. The sustainability assessment framework leads to sustainability indicators that are used to assist policy makers and decision-making processes. The literature review shows that the energy systems are suited to sustainability assessment with exergy based assessment tools and indicators from an environmental point of view. In this study, an exergy based sustainability assessment is carried out by using the exergy analyses results of an ORC (organic Rankine cycle) integrated waste heat recovery system on a 1,221 TEU container ship. The exergy analysis results are used to derive comparable and quantified exergetic sustainability indicators that indicate the sustainability level and further improvement potentials with the utilization of the proposed waste heat recovery system design. The assessment results show that the minimum waste exergy ratio is obtained from R1234ze(Z) at 3 MPa with the value of 0.106. R1234ze(Z) and R245fa working fluids show good environmental performance for the proposed system design. The maximum exergetic sustainability index values are obtained from R1234ze(Z) and at 3 MPa at the value of 8.435.

Energy audit and waste heat recovery system design for a cement rotary kiln in Ethiopia: A case study

This paper deals with the energy audit and heat recovery system modeling and design , taking a cement factory in Ethiopia as a case study. The system is a dry type rotary kiln equipped with a sixth stage cyclone type preheater , pre - calciner and grate cooler. The kiln has a capacity of 3 , 000 tons/day. The energy auditing has been performed based on the data collected from control volume of the kiln system for a ten - month period . The result shows that 25.23% of the total heat input is released to the environment through the preheater and an other 15.58% through the cooler exhausts. The west heat recovery system (WHRS) can produce a gross power of 5.26 MW as long as the kiln is i n operation . The generated power can cover all the electrical energy consumption of the kiln system whether there is a power supply from the grid or not. Therefore, the company can save up to 536,222.10 USD per year due to the production of clinker using their own power source and avoiding the loss sustained by the company due to power interruption from the grid

Heat and Mass Transfer Analysis of Mine Exhaust Air Heat Exchanger

As a good energy resource, Mine exhaust air has an important value of recycling. In this paper, the heat and mass exchange mechanism and potential of the mine exhaust air heat exchanger (MEAHE) is mainly researched. The heat exchanger efficiency is affected by water and air temperature and flow in terms of double efficiency method. The result can provide the basis for the further determine the thermal calculation method for MEAHE, and lays the foundation for the mine comprehensive utilization of waste heat recovery system design.

Design to Maximize Performance of a Thermoelectric Power Generator With a Dynamic Thermal Power Source

It is a difficult technical challenge to design thermoelectric power generation systems that work optimally over a broad dynamic range of thermal input power. Conventional systems are designed to work optimally for a nominal operating condition, while maintaining the ability to operate at off nominal and extreme operating conditions without damage to the system. For systems that operate in a narrow range of thermal power conditions, thermoelectric waste heat recovery system design is simplified. However, for applications that do have a wide range of operating conditions, designs typically exhibit overall average efficiencies that are reduced by approximately 20% or more compared with that achievable for the thermoelectric material operating at peak efficiency. Both cars and trucks consume significant fuel at low mass flow rates. Since the ultimate goal of waste heat recovery systems is to minimize fuel consumption, it is critical that the recovery system be designed to operate near peak efficiency over the range of mass flow rates that make a significant contribution to overall power recovery. Such performance capability is especially important in city driving, and in hybrid vehicle applications. This paper describes a design concept that maximizes the performance for thermoelectric power generation systems in which the thermal power to be recovered is from a fluid stream (e.g., exhaust gas) subject to varying temperatures and a broad range of exhaust flow rates. The device is constructed in several parts, with each part optimized for a specific range of operating conditions. The thermoelectric system characteristics, inlet mass flow rates and fluid temperatures, and load and internal electrical resistances are monitored and generator operation is controlled to maximize performance. With this design, the system operates near optimal efficiency for a much wider range of operating conditions. Application of the design concept to an automobile is used to show the benefits to overall system performance.

Thermo-electric generator

Thermal management and energy crisis have been two major problems in this 21st century. Engine exhaust has tremendous amount of energy which can be recovered by waste heat recovery systems. The thermoelectric concept is seen as a perfect solution for recovering waste heat from engine exhaust and converts in to electric energy. Since the use of semiconductor materials for thermoelectric applications, there has been a huge quest for improving its figure of merits (ZT) to make it commercially viable. This synopsis report presents the simulation and experimental validation study on the transient behavior of a proposed combined exhaust heat recovery device and thermoelectric power generation system. The proposed system consists of waste heat recovery that provides a heat flux source for thermoelectric generators. In this research, thermoelectric generator device are consist of two major part, first one is exhaust recovery device and second one is thermoelectric generation system. In the first phase of study, optimize the waste heat recovery system design, performed cfd analysis and get heat and temperature data then cfd model coupled with thermoelectric model, find out the thermoelectric effect on particular devices. This paper presents of numerical simulation for several the thermoelectric materials. Numerical simulation is carried out by using a finite element package ANSYS.