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Proposed Test Methodology and Performance Rating Standard for Residential Fuel Cell Systems.


pdf icon Proposed Test Methodology and Performance Rating Standard for Residential Fuel Cell Systems. (557 K)
Davis, M. W.; Ellis, M. W.; Dougherty, B. P.

NISTIR 7131; 85 p. June 2006.

Keywords:

fuel cells; test methods; classifications; equipment; computation; data analysis; systems performance; standards; energy systems; climate

Abstract:

A test method and rating standard is proposed for residential fuel cell systems (RFCSs). The proposed approach extends previously developed test procedures for fuel cells by establishing specific test methods and calculation procedures that are applicable to residential fuel cell systems. These methods and procedures provide the end user with metrics that can be used to evaluate the merit of a RFCS in a particular application. In the proposed standard, RFCSs are classified into four types: Type I - Grid independent, electrical load following; Type II - Grid interconnected, constant power; Type III - Grid interconnected, thermal load following; and Type IV - Grid interconnected, water heating. Test procedures are described that yield simplified models for the performance of each system based on appropriate load characteristics and ambient conditions. For Type I systems, the steady fuel use, thermal energy output, and water use are expressed as functions of the electrical part-load ratio and the ambient temperature. In addition, the thermal energy output, electrical output, fuel use, and water use (for RFCS humidification) associated with a hot water simulated use test are evaluated as functions of electrical part-load ratio and ambient temperature. Transient electrical load factors are measured and applied to the thermal energy output and the fuel consumption to incorporate the system's performance under transient electrical loads. For Type II systems, electrical power remains constant and the steady fuel use, thermal energy output, and water use are expressed as functions of ambient temperature. In addition, the thermal energy output, electrical output, fuel use, and water use (for RFCS humidification) associated with a hot water simulated use test are evaluated at rated power and specific values of ambient temperature. For Type III systems, the system output follows the thermal load and the steady fuel use, electrical output, and water use are expressed as functions of thermal part-load ratio and ambient temperature. In addition, the electrical output, fuel use, and water use (for RFCS humidification) associated with a hot water simulated use test are evaluated at specific values of ambient temperature. For Type IV systems, the system operates to meet the hot water requirement and the thermal energy output, electrical output, fuel use, and water use (for RFCS humidification) associated with a hot water simulated use test are evaluated at specific values of ambient temperature. For each system type, steady and simulated use models are combined to predict the performance of the system in response to typical residential electrical and thermal loads for various representative climates. For units that draw ventilation air from the indoors, the performance is corrected to account for the energy required to condition outdoor air to replace the ventilation air. The annual performance is expressed in terms of the impact on the end user's net electricity use (or generation), fuel use, and water use.