Monarch Instrument DC6000 - Manual (Page 59)

Section 5 – Recorder Setup
I.
Page 51
1/06/2012 REV 1.10.2
5.1.3.1 Energy
This is another case of a special calculation channel for calculating energy in hot or chilled water
systems. (For Steam see below). It uses external inputs to measure process input and output
temperatures and flow and uses look up tables (Enthalpy Steam Tables) and mathematics to compute the
energy. The formula is basically
Energy = Mass Flow x Enthalpy
Where Mass Flow is the Flow x Density and the Enthalpy is the difference in Enthalpy between inlet and
outlet temperatures. This calculation is for hot/chilled water based systems and uses density calculation
for water and the Keenan and Keyes Steam tables to derive the Enthalpy.
Select a channel type of Energy. This will bring up the
Energy Setup dialog box. There are three external
inputs required by the system
– two temperatures and
flow, these need to be set up beforehand on the
individual
channels referenced. An additional
temperature to control density can be used - see below:
Flow: Select the channel the flow meter is on and the
units the flow is measured in using the drop down
menus. Choices for flow are GPM, m
3
/hr and ft
3
/min – if
these are not your flow measurements you need to
prescale this input accordingly.
Supply/Return Temps: Select the channels for
temperature measurement of the inlet and outlet points
for system temperatures. Temperatures can be in either °F or °C. The unit will adapt for hot or chilled
water systems accordingly.
Energy Units: Select the resulting units for display – options are BTUs, Watts or Joules at varying rates.
Density: The density is that of the water and it is depends on the pressure and temperature. It can be
calculated or manually entered. In order to calculate it you need to enter the following before calculating:
Pressure: Enter the water pressure in the units selected (Check PSI or bar or kPA)
Temperature: The temperature can be entered manually or can come from an input channel.
From the drop down menu choose MAN to manually enter the temperature or
choose an input channel to be used for temperature and select the engineering
units (degF or degC).
To calculate the density once the pressure and temperature have been entered press the
calculate button. If manually entering the density select the engineering units from the drop
down menu.
Apply: Save the values and exit Cancel: Exit without making any changes
Fig 5.16 – Energy Setup