Reference no: EM13997551

Problem Statement:

The ML-1 reactor (mobile low power reactor 1) was a Brayton cycle nitrogen-cooled, water-moderated reactor designed by Aerojet-General Corporation. This was part of the United States Army Nuclear Power Plant Program (USANPP) and like many reactors in this program; it had a power rating less than 2 MWe. This reactor plant was transported on standard army trailers. The purpose of the ML-1 power plant was to provide electrical power to remote locations. It was intended to provide power to run a field hospital. The ML-1 reactor was during the years of 1961-1964. By 1965, all power plants of the USANPP had been phased out. Figure 1 shows a schematic of the ML-1 plant system. In Tables 1-4 show some relevant data pertaining to the ML-1 design.

Figure 1. Schematic of ML-1 plant system

Table 1. General information on temperatures, pressures, etc

Particulars		Information
Design ambient temperature		100 °F
Coolant		Nitrogen gas
Coolant flow		95000 lb/hr
Compressor inlet temperature		132 °F
Compressor inlet pressure		117 Psia
Compressor outlet temperature		366 °F
Compressor outlet pressure		320 Psia
Reactor inlet temperature		791 °F
Reactor inlet pressure		313 Psia
Turbine inlet temperature		1200 °F
Turbine inlet pressure		289 Psia
Turbine outlet temperature		901 °F
Turbine outlet pressure		120 Psia
Pre-cooler inlet temperature		479 °F
Pre-cooler inlet pressure		118 Psia
Table 2. Turbine-compressor set details
Particulars		Radial Flow Compressor
Speed
Turbine stages
Turbine rotor material
Turbine blade material
Turbine stator blade material
Expansion ratio
Compressor stages
Compression ratio
Table 3. Recuperator details
Particulars		Details
Length		81 inches (with external insulation)
Outside diameter		45 inches (with external insulation)
High pressure inlet (header dimension)		8 inches
High pressure outlet (header dimension)		8 inches
Low pressure inlet (header dimension)		20 inches
Low pressure outlet (header dimension)		14 inches
Effectiveness		80.75%
High pressure loss percentage Δp/p		1.61%
Low pressure loss percentage Δp/p		1.06%
Type		Shell and tube regenerator

Table 4. Pre-cooler details

Particulars	Details
Pre-cooler length	128 inches
Width	113 inches
Thickness of pre-cooler core	15 inches
Thickness of fans and plenums	17 inches
Material of tubes and fins	Series 1100 aluminum
Material of headers	Series 2219 aluminum
Pre-cooler header, inlet	14 inches
Pre-cooler header, outlet	10 inches
Effectiveness	93%
Total Δp/p	1.55%
Air flow	289,000 lb/hr
Type	Fin fan air-to-gas exchanger
Tubes	1131 tubes, single pass
Surface	Internal and external fins

Question 1:

Calculate the thermal efficiency of the ML-1 nuclear plant using the information provided in Table 1-4. Please note that you may not need to use all the information provided. Figure 2 shows a simplified version of Figure 1. Figure 3 shows a T-S diagram that corresponds with Figure 2. Please show all work.

Figure 2. Simplified diagram of ML-1 plant system

Figure 3. Temperature-entropy (T-S) diagram of ML-1 plant system

Question 2:

In Figure 4, a 2^nd recuperator (R2) of the same model has been added. Flow control valves have been added to divide the flow going to R1 and R2 from the turbine and the compressor. Find values of the mass flow rates such that the thermal efficiency is greater than that of Question 1.

Figure 4. ML-1 plant system with an additional recuperator