China
Africa
Explore chapters and articles related to this topic
Heating, Ventilation, and Air Conditioning (HVAC) Systems
Published in Scott Dunning, Larry S. Katz, Energy Calculations & Problem Solving Sourcebook, 2020
A Waste Heat Recovery Unit (WHRU) is a heat exchanger that recovers heat from a hot gas stream while transferring it to a working medium, typically water or oils. The hot gas stream can be the exhaust gas from a gas turbine or a diesel engine or a waste gas from industry or refinery.Big systems with high volume and temperature gas stream, typical on industry, can benefit from Steam Rankine Cycle (SRC) in a WHRU.The recovery of heat from low temperature systems requires more efficient working fluids than steam.An Organic Rankine Cycle (ORC) WHRU can be more efficient at low temperature range using refrigerant that boils at lower temperatures then water. Typical organic refrigerants are Ammonia, Pentafluoropropane(R-245fa and R-245ca), and Toluene.
Energy and exergy analysis of a solid-oxide fuel cell power generation system for an aerial vehicle (ISSA- 2015–139)
Published in International Journal of Green Energy, 2018
As is shown in Figure 1, the considered solid-oxide fuel cell/gas turbine hybrid power generation system mainly consists of power generation unit and waste heat recovery unit. While solid oxide fuel cell, Direct-Current/Alternating-Current inverter, air compressor and gas turbine are used in the power generation unit, heat exchanger, degasser and economizer are used in the waste heat recovery unit. The system is fed by methane. The power plant generates electricity and steam based on the standard Brayton cycle using CH4.
A study on the design of Waste Heat Recovery Unit (WHRU) for 30kW Organic Rankine Cycle (ORC) power system for ships
Published in Journal of International Maritime Safety, Environmental Affairs, and Shipping, 2023
Dae Jung Hwang, Jae Hoon Jee, Jung Sik Kim, San Kim, Cheol Oh
This numerical analysis is a heat flow analysis for a waste heat recovery unit (WHRU) as an element technology in an ORC-based power generation system that uses exhaust gas discharged from a ship’s main engine as a source of heat energy and refrigerant R134a as a working fluid. This was done through the ANSYS CFX (v.18.1) program. While changing the design elements (shape, pipe diameter, number of pipes, number of stages, etc.) of the waste heat recovery device to be developed, a WHRU capable of achieving 30 kW power generation output performance was designed. As a result, the following conclusions were obtained within the subject of this analysis and the calculation conditions and scope. It was confirmed that the refrigerant (R134a) in a liquid state at a temperature of 14.8°C entered at a flow rate of 1.06 kg/s, evaporated by the exhaust gas, and was discharged from the outlet in a state of vapor fraction 1 at a temperature of 56.4°C. The heat transfer rate of the WHRU was 219.2 kW, the pressure during the evaporation process was constant at 13.9 bar in absolute pressure, and the enthalpy was 220 kJ/kg at the inlet and 426 kJ/kg at the outlet, respectively.In the WHRU, exhaust gas enters from the bottom and is discharged from the top. Under the conditions of exhaust gas flow rate of 34 kg/s and inlet temperature of 160°C, the pressure difference between inlet and outlet was 201.4 mmH2O. The exhaust gas flow rate and temperature used in the simulation are conditions considering the actual test operation situation of the WHRU, and it should be taken into account that the exhaust gas temperature of the operating ship is actually higher than 160°C.One inlet pipe was installed at the refrigerant inlet and two pipes were installed at the outlet. This is a measure to ensure a uniform flow of refrigerant is distributed to the 10 tubes installed inside the WHRU. In this design study, a uniform flow distribution was attempted by installing two outlet pipes in a balanced way, but since this is associated with an increase in manufacturing cost, it is necessary to review other methods that can adjust the flow rate, such as inserting an orifice in the pipe, depending on the manufacturing situation.