Performance of solar thermal systems with liquid metal MHD conversion
Liquid metal magnetohydrodynamic conversion (LMMHD) is found to be compatible with concentrating solar receivers employing a liquid metal as a heat transfer medium and offers significant increases in the system thermal efficiency over the 33% considered attainable with conventional turbo-machinery. There are two candidate liquid metals - sodium and lithium. With sodium at a temperature of 1150/sup 0/F (922/sup 0/K), the maximum calculated efficiency is 39.5% while with lithium at 1400/sup 0/F (1033/sup 0/K) a peak efficiency for 46.5% is predicted. Up to two percentage points may be added by temperature increase and/or parameter limit relaxation in the sodium case. The sodium-steam heat exchanger is eliminated in liquid metal systems. Where LMMHD systems employ the same working fluid as the solar receiver, no recirculating pump is required as pumping power is provided directly by the cycle. For sodium, coupling with either a gas turbine or a steam turbine is beneficial and provides similar performance. With lithium, the gas turbine cycle is clearly superior. Sodium systems can be based on existing materials experience while the use of lithium will require an engineering development effort to establish suitable materials for containment. The existing sources of LMMHD data are generally sufficient for establishing a preliminary engineering basis for conceptual studies. An exception is the dc to ac power conditioning sub-system where further study is required. The design of concentrating solar receivers requires revisiting to accommodate the particular characteristics of the LMMHD system and its potential for operating at temperatures above those of conventional steam turbo-alternator systems.
- Research Organization:
- HMJ Corp., Chevy Chase, MD (USA)
- DOE Contract Number:
- AC03-83SF11943
- OSTI ID:
- 6285064
- Report Number(s):
- DOE/SF/11943-T1; ON: DE85002758
- Country of Publication:
- United States
- Language:
- English
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30 DIRECT ENERGY CONVERSION
LIQUID-METAL MHD GENERATORS
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EFFICIENCY
GAS TURBINES
LITHIUM
SODIUM
ALKALI METALS
DIRECT ENERGY CONVERTERS
ELEMENTS
EQUIPMENT
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