Applicable throughout its two-stroke engine programme, MAN Energy Solutions offers exhaust gas recirculation (EGR) in parallel to selective catalytic reduction (SCR) as an option for meeting IMO Tier Ⅲ stipulations. Recent confirmation that EGR would be available for the latest addition to the portfolio, the ME-GA dual-fuel low-speed design not only ensures the requisite level of environmental compliance in all operating modes but also delivers a raft of performance benefits. The ME-GA is the low-pressure, Otto-cycle variant of the established ME-GI high-pressure dual-fuel series. In gas mode, the ME-GA engine meets Tier Ⅲ NOx emission criteria. By incorporating EGR, a vessel powered by ME-GA machinery will remain Tier Ⅲ-compliant when operating on fuel oil. The technology obviates the need for additional exhaust aftertreatment. The test campaign carried out at the company's research centre in Copenhagen covered evaluation of EGR on the ME-GA engine running in both diesel and gas modes. While effectiveness in NOx abatement was verified, it was additionally found that EGR improved engine performance with either fuel. Thus, compared to a 'standard' ME-GA without EGR, it was demonstrated that application of EGR would reduce both specific gas consumption (SGC) and specific fuel oil consumption(SFOC). When operating in gas mode, SGC is lowered by approximately 3% across the complete load range, and SFOC is brought down by some 5% in diesel mode.
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