Column 5: Proposed average input kW (BLUE):
The values in the 'Proposed' or BLUE column use the same calculations. Variation between the 'Installation' or RED column and the BLUE column is derived from...
- Re-ordering the equipment on the BLUE line
- Changing the pressure settings of the equipment on the BLUE line
- Removing equipment from the BLUE line
- Adding alternative equipment to the BLUE line
- Enabling Metacentre system control
- Changing the target pressure of the BLUE line
Column 6: Input kW variance of BLUE compared to RED:
Column 6 = Column 4 minus Column 5
Columns 7 & 8 displayed in 'Annual' Simulation only:
Column 7: Annual kW variance of BLUE compared to RED:
Column 7 = Column 6 expressed in kW hours per annum
Column 8: Annual monetary variance of BLUE compared to RED:
Column 8 = Column 7 expressed in monetary terms using the average kW hour tariff
Columns 7, 8 & 9 displayed in 'Time span' Simulation only:
Column 7: Savings:
Column 7 = Column 6 (kW variance) x Column 2 (utilisation hours)
Column 8: kW savings per annum:
Column 8 = Column 7 extrapolated to 1 year...
- Remove 'system shutdown hours' from 8760 (1 year in hours) (so in the example image above, system shutdown hours is 2000 hours so this will leave 6760 hours where the system was either operating within a segment (e.g. 0 - 10%) or operating 'off load' or 'stopped')
- Take the utilisation hours (column 2) for a segment or 'off load' or 'stopped' and extrapolate accordingly. For example...
- Lets assume that column 2 for 0 - 10% is 100 hours
- And that the sum of all segments (including 'off load' or 'stopped') was 200 hours.
- 100 / 200 * (8760 - 2000) = 3380
- Finally, multiply the above result (extrapolated utilisation hours for a segment) with column 6
Column 9: Savings per annum
Column 9 = Column 8 expressed in monetary terms using the average kW hour tariff
Point 1: Simulation Wizard rule applied to 'off load' kW when Metacentre system control is enabled:
Fixed speed equipment:
On the BLUE line, Metacentre system controller can change the equipment used to produce the same flow when compared to the RED line. In other words, for the 'entire span' of the output flow, other equipment used also means other equipment operating in an offload state from time to time. Since a Metacentre system controller always uses the most efficient equipment available, logic says that an overall gain must be achieved during periods of time whilst operating off load.
The specific efficiency curve (shown below) takes into account that some equipment is running 'fully loaded' whilst one item of equipment will operate either loaded or unloaded (off load). This is calculated during the system load time. The installation as such will also operate unloaded or off load from time to time (Due to equipment 'no load' run timers etc). These hours are also taken into account and they are independent of pressure.
Whilst operating off load, equipment is operating to 'free air', it's therefore difficult to identify which item of equipment will be the one operating. The percentage equipment is present on the output span provides an indication of 'how big' the probability is that an item of equipment will contribute to offload kW.
The following example shows how Simulation Wizard calculates this gain...
A 3 compressors scenario:
Full load kW
Average output kW over entire output span on RED line:
((C1 offload kw x C1%span) + C2 offload kw x C2%span) + C3 offload kw x C3%span) +) / total span =
(29.0 * 55% + 24 * 33% + 12.5 * 12%) / 100% = 25.37
Looking at the BLUE line you can see that over the entire span, the smallest (most efficient) item of equipment is used in 3 different areas, the middle size item of equipment in 2 different areas and the least efficient item of equipment only once. This fundamentally changes the 'span %' different equipment operates and favors the more efficient equipment to be operating in a load or off load state.
Once again, looking at the BLUE line in the example, you can see the smallest item of equipment is used 3 times over the entire output span. The middle is used on 2 occasions. Again, it is 'efficiency' which determines which item of equipment is used more often. Using a more efficient item of equipment, reduces the %span of less efficient equipment. The calculation for the BLUE line is as follows:
Average output kW over entire output span on BLUE line:
C1%new = C1%span – C2%span
C2%new = C2%span – C3%span
C3%new = C3%span – 0
((C1 offload kw x C1%new) + C2 offload kw x C2%new) x 2 + C3 offload kw x C3%new * 3) +) / total span =
(29.0 * 22% + 24 * 21% * 2 + 12.5 * 12% * 3) / 100% = 20.96
Average offload kW ratio = average BLUE / average RED
20.96 / 25.37 = 0.826 or 82.6 %
Conclusion for fixed speed equipment:
For any off load kilowatt consumed on the RED line, 82.6% will be consumed on the BLUE line or a gain of 17.4%
Variable speed equipment:
The variable speed scenario is more difficult to predict. Theoretically, off load operating times could or should be run down to zero 'IF' all equipment is appropriately sized. However, when fixed speed equipment variants are used in combination with variable speed equipment, off load operating likely cannot be avoided and will result in some off load kW consumption. The overall benefit will be greater due to the introduction of variable speed equipment. To demonstrate the significant benefit of introducing variable speed equipment when compared to fixed speed equipment yet retain some unavoidable off load kW, a reduction of 50% is used to calculate off load kW.
Conclusion for variable speed equipment:
Introducing variable speed equipment will always show a meaning full reduction inclusive off load.
Where system shutdown data originates:
For Simulations that are not linked to an audit, system shutdown hours are hypothetical.
For Simulations linked to an audit, system shutdown hour data data originates from Audit Wizard step 3 'create site & energy profile'
The chart coloured 'GREEN' or 'RED' area:
The chart coloured area summarises annual kW consumption for the equipment configuration on the RED line, annual kW consumption for the equipment on the BLUE line alongside annual savings for kW hours, monetary cost and CO² emissions.
The chart coloured area will be GREEN when the results of BLUE are better than RED. Conversely the chart coloured area will be RED when the results of RED are better than BLUE.