ASME PTC-50:2002 pdf free download FUELCELL POWERSYSTEMS PERFORMANCE
(d)Fuel Processing. Involves a variety of pro-cesses,depending on the fuel cell types. if the fuelcell is running on bottled hydrogen,fuel processingis minimal. Typically a fuel celi power system wilibe run on common hydrocarbon fuels，such asnatural gas.Fuel processing usually involves cleaningto remove possible fuel cell poisons (e.g.， sulfurcompounds used in natural gas odorants). lt caninclude reforming of the gas to produce hydrogen(in“externally reformed” systems) or this functioncan occur inside the stacks in some types of fuelcells. The fuel processor may also include otherequipment, such as shift reactors, cO oxidizer reac-tors,higher hydrocarbon removal,etc.
(e) Heat Recovery. Systems in fuel cell powersystems usually consist of fairly conventional heatexchange equipment, which is used to extract wasteheat (typicaily from the system exhaust stream) toprovide reactant pre-heat and steam generation.(f)Oxidant Supply. Usually consists of a meansof providing fresh air to the system,typically witha blower or compressor.
(g)Power Conditioning. Involves conversion ofthe DC power output from the electrochemical fuelcells to useful power.This usually involves inversionto produce AC power suitable for the intendedpurpose,but it can also include the production ofregulated DC or“chopped”DC.
2.4GENERAL FUEL CELL NOMENCLATURESome of the common terms used to describe fuelcell power system components are as follows:(a) Fuel Cells. Individual electrochemical cellsthat produce a voltage (typically 0.5 V to 1 v each)when provided with a supply of fuel and oxidant.Fuel cells consist of an anode (where fuel is con-sumed and electrons are liberated), a cathode (whereoxidant is consumed and electrons are captured),and an electrolyte that provides a path for transferof ions between the anode and cathode reaction sites.(b) Fuel Cell Stacks.Consist of a group of individ-ual fuel cells that are physically held together in astack or a bundle, are fed fuel and oxidant flowstogether, and whose electrical output is combined.Fuel cell stacks may be configured individually,combined into multistack modules,or they may beconfigured as part of a fully self-contained powersystem.
(c) Balance of Plant (BOP). Used to refer to all components in a fuel cell power system besides theelectrochemical fuel cell stacks. The BOP can in-clude fuel processing equipment, heat recoveryequipment，power conversion equipment，controlequipment，etc.
2.5 GENERAL DEFINITIONS
accuracy: the closeness of agreement between ameasured value and the true value.
base reference conditions:the values of all theexternal parameters; i.e., parameters outside the testboundary to which the test results are corrected.Also, the specified secondary heat inputs and outputsare base reference conditions.
bias error: see systematic error.
calibration: the process of comparing the responseof an instrument to a standard instrument over somemeasurement range and adjusting the instrument tomatch the standard, if appropriate.
calibration drift:see para. 4.1.3.6.calibration shift: see para. 4.1.3.6.
consistent liquid or gaseous fuels: fuels with aheating value that varies less than one percent overthe course of a performance test.
electric efficiency: the ratio of the electrical energyoutput to the energy supplied to the power systemexpressed as a percentage. lt is inversely related toheat rate.
emissions: nuisance discharges from power plantsystems which are regulated by authorities havingjurisdiction,such as air pollutants，waste streamsand noise.
heat input:the flow of fuel(s) multiplied by thehigh or low heating value of the fuel(s).
heat rate [kJ/kW-h or Btu(kW-hl: heat input perunit of power output, based on either the low orhigh heating value of the fuel.
heat sink:the reservoir to which the heat rejectedby the system is transferred. For a cooling pond,river，lake,or ocean cooling system,the reservoiris the body of water. For an evaporative or dry air-cooled heat exchanger system, the reservoir is theambient air.