WHICH FEATURES SHOULD BE INCLUDED

Some of the design features which Enviropower consider to be important and which are standard:-
• Sump removable from engine without removing the complete engine from the site - one day engine maintenance will be necessary.
• Exhaust temperature maintained above dew point to avoid plume of water vapour and potential corrosion - particularly important for biogas fuels. Set mounted oil make-up tank and automatic replenishment system - so you do not have to look at the machine very often.
• Low oil pressure, low water level, high water temperature and low oil level shutdown switches - the best designed and built machines occasionally have problems and you do not want a simple leak to become a complete engine breakdown .
• Shell and tube heat exchangers - rarely become blocked and are much more efficient in minimising pump power.
• Alternator specified for class "F" temperature rise - to ensure long alternator life.
• Engine rated for continuous duty - many engines have their power quoted at maximum duty. We expect engines to last many thousand hours so derates are applied.
• Electronic governors for reliable synchronisation and load sharing.

Some of the features which may or may not be necessary:-
• Integral acoustic enclosure / "drop over" acoustic enclosure.
• Residential / Industrial standard of acoustic enclosure.
• Service connection points variable in size and position. (fuel input, circulating water supply and return, exhaust pipe location
• Gas pressure booster if necessary.
• Control panel locally (on enclosure) or remotely mounted.
• Machine specified for series or parallel heating systems
• Secondary circulating water pump - set mounted.
• 50 Hz / 60 Hz electrical connection.
• Alternative temperatures.
• Automatic mixture controllers for gases of variable quality.
• External, extra cooling systems for when there is no heat demand.
• "Tracking" of site's electricity import/export to ensure that at no time does CHP set export to grid.

Based on using gas engines with fuel similar to British Natural Gas with LCV of 34 MJ per cubic metre, the following is a table of typical performances. Intermediate outputs would be covered by using the next larger size and controlling engine output if necessary.

Smaller machines can be built.

Other engine makes will give intermediate outputs.

Electrical Output	Cylinder arrangement	Engine Maker	Heat Outputs and Temperatures
57 kW	I-6 N/A	Iveco	Jacket and exhaust 70 kW
110 kW	I-6 N/A	Perkins	Jacket and Exhaust 184 kW Water inlet.outlet temps 70/83.3oC
150 k	I-6 T/C	Perkins	Jacket and exhaust 230 kW Water inlet/outlet temps 70 / 86.4oC
225 kW	V-12 N/A	Perkins	Jacket and exhaust 230 kW Water inlet/outlet temps 70 / 86.4oC
300 kW	I-6 T/C I/C	Perkins	Intercooler 40 kW Jacket and exhaust 400 kW Water inlet/outlet temps 80 / 86oC
400 kW	I-8 T/C I/C	Perkins	Intercooler 50 kW Jacket and exhaust 570 kW Water inlet/outlet temps 77 / 95oC
600 kW	V-12 T/C I/C	Perkins	Intercooler 80 kW Jacket and exhaust 900 kW Water inlet/outlet temps 75 / 90oC
800 kW	V-16 T/C I/C	Perkins	Intercooler 90 kW Jacket and exhaust 1100 kW Water inlet/outlet temps 65 / 85oC
1000 kW	V-16 T/C I/C	Perkins	Intercooler 70 kW Jacket and exhaust 1170 kW Water inlet/outlet temps 70 / 81.5oC

These are typical and indicative only, though drawn from real applications. They are all at 1,500 rpm, at sea level and in UK ambient conditions.

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