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Research Papers: Heat Energy Generation/Storage/Transfer

# Performance of a Novel Semiclosed Gas-Turbine Refrigeration Combined Cycle

[+] Author and Article Information
Joseph J. Boza

Naval Warfare Center, 110 Vernon Avenue, Panama City, FL 32407

William E. Lear

Department of Mechanical and Aerospace Engineering, University of Florida, P.O. Box 116300, 232 MAE Building B, Gainesville, FL 32611-6300sasherif@ufl.edu

S. A. Sherif1

Department of Mechanical and Aerospace Engineering, University of Florida, P.O. Box 116300, 232 MAE Building B, Gainesville, FL 32611-6300sasherif@ufl.edu

1

Corresponding author.

J. Energy Resour. Technol 130(2), 022401 (May 16, 2008) (11 pages) doi:10.1115/1.2906034 History: Received January 13, 2004; Revised October 22, 2007; Published May 16, 2008

## Abstract

A thermodynamic performance analysis was performed on a novel cooling and power cycle that combines a semiclosed gas turbine called the high-pressure regenerative turbine engine (HPRTE) with an absorption refrigeration unit. Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration cycle, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration depending on ambient conditions. Two cases were considered: a small engine with a nominal power output of $100kW$ and a large engine with a nominal power output of $40MW$. The cycle was modeled using traditional one-dimensional steady-state thermodynamics, with state-of-the-art polytropic efficiencies and pressure drops for the turbomachinery and heat exchangers, and curve fits for properties of the LiBr-water mixture and the combustion products. The small engine was shown to operate with a thermal efficiency approaching 43% while producing 50% as much $5°C$ refrigeration as its nominal power output (roughly $50tons$) at $30°C$ ambient conditions. The large engine was shown to operate with a thermal efficiency approaching 62% while producing 25% as much $5°C$ refrigeration as its nominal power output (roughly $20,000tons$) at $30°C$ ambient conditions. Thermal efficiency stayed relatively constant with respect to ambient temperature for both the large and small engines. It decreased by only 3–4% as the ambient temperature was increased from $10°Cto35°C$ in each case. The amount of external refrigeration produced by the engine sharply decreased in both engines at around $35°C$, eventually reaching zero at roughly $45°C$ in each case for $5°C$ refrigeration. However, the evaporator temperature could be raised to $10°C$ (or higher) to produce external refrigeration in ambient temperatures as high as $50°C$.

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## Figures

Figure 1

The HPRTE cycle

Figure 2

The HPRTE and absorption refrigeration combined cycle

Figure 3

Dual combustor model

Figure 4

ηth, ηcomb, and β versus ambient temperature for the large engine

Figure 5

ηth and β versus ambient temperature for evaporator temperatures of 5°C and 10°C for the large engine

Figure 6

ηth, ηcomb, and β versus generator temperature for the large engine

Figure 7

ηth and β versus turbine inlet temperature for turbomachinery polytropic efficiencies of 90% and 93% for the large engine

Figure 8

ηth, ηcomb, and β versus recuperator inlet temperature for the large engine

Figure 9

ηth, ηcomb, and β versus low-pressure compressor pressure ratio for the large engine

Figure 10

ηth, ηcomb, and β versus ambient temperature for the small engine

Figure 11

ηth and β versus ambient temperature for evaporator temperatures of 5°C and 10°C for the small engine

Figure 12

ηth, ηcomb, and β versus generator temperature for the small engine

Figure 13

ηth and β versus turbine inlet temperature for turbomachinery polytropic efficiencies of 90% and 93% for the small engine

Figure 14

ηth, ηcomb, and β versus recuperator inlet temperature for the small engine

Figure 15

ηth, ηcomb, and β versus LPC pressure ratio for the small engine

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