Progress on the Investigation of Coal-Water-Slurry Fuel Combustion in a Medium-Speed Diesel Engine: Part 3—Accumulator Injector Performance

Abstract

Coal-water-slurry (CWS) engine tests designed to evaluate a new accumulator-based injection system are described in this paper. The new injection system was found to improve CWS burnout considerably at both full and part engine loads. The peak cylinder firing pressure when operating with CWS was no higher than when operating with diesel oil. These data demonstrate the improved engine performance that can be achieved with the accumulator-based injection system.

Combustion characteristics of a charcoal slurry in a direct injection diesel engine and the impact on the injection system performance

“…The injection system that Hsu and Leonard [7] investigated was based on an accumulator and diaphragm type using CWS and a diesel pilot. They found that coal had to be ash cleaned as low as 0.8% at an average particle diameter of 5.5 mm with slurry viscosities of about 150e250 cP.…”

DI diesel engine operated with carbon-black-water-diesel slurry at different injection timing and nozzle opening pressure

“…The new accumulator based injector reduced the ignition delay by increasing the nozzle opening pressure in the range of 27.6MPa-53.7 MPa, early in the injection cycle. It was further reported that the accumulator based injection system provided a satisfactory combustion of CWS [13]. The use of MCWS at high nozzle opening pressures of 40 to 140 MPa, in a single cylinder, 4-stroke Cooper JS-1 diesel engine with a speed range of 300-450 rpm, showed that the cone angles and fuel-air mixing increased rapidly with the relatively constant cone angles of diesel.…”

Clean Coal Diesel Demonstration Project

“…Likos and Ryan (23) used both CWS and coal powder in a high-swirl, high temperature pre-chamber engine, as did Kakwani (64,65). The vast majority of the engine experience, however, has been reported by Hsu et al (35,[66][67][68][69][70][71] and Rao et al,(28,72) each using two different 4-stroke medium-speed engines. Schwalb (2l) reported successful operation in a 2-stroke high-speed diesel engine operating in compression ignition mode.…”

“…The combustion efficiency was increased to 99 percent and the conclusions regarding the injection timings were later modified after the compression ratio was increased to 13: 1 (68), and the CWS injection pressure was increased to 83 MPa (69) using an accumulator injection nozzle (Figure 58), and the number of holes in the injection nozzle tip reduced from 10 to 8 with the same total flow area (69). It was concluded that it was best to inject the CWS as early as 35° BTDC and to wait as long as possible to inject the pilot (120 BTDC) in order to allow time for mixing and evaporation of the water from the slurry.…”