An energy audit
requires the on-going performance of a water to air heat exchanger
to be measured, calculated and reported daily. The client
is looking for hourly and daily performance. The solution
is to use a standard HyperLogger or ModuLogger MINI with temperature
and flow data being recorded and processed every 5 seconds.
Heat Exchanger Instrumentation:
Two type K thermocouples are used, one placed on
the inlet and outlet of the heat exchanger. The other sensor
is a flow meter to record flow and allow for the calculation
of pounds of water per minute.
Hyperware Program Net Description:
The actual temperature of the water flowing into and out of
the heat exchanger is measured with two K type thermocouples.
The differential temperature (DeltaT) is then calculated with
a Math Icon.
The flow rate of the liquid through the heat exchanger coils
is measured with a 4-20mA output flow meter. The 4-20mA output
representing the flow rate is converted to pounds of water
per minute within a Math icon. The conversion is done using
the flow meter manufacturer's conversion spec (4-20mA corresponds
to 0-60GPM) and the known mass of water per gallon (8.3453).
The DeltaT and the mass flow rate are then
multiplied within a Math Icon to result in the 5 second instantaneous
heat transfer rate in BTU/Min. This heat transfer rate is
then integrated over repetitive hourly periods and the resulting
hourly BTU totals are stored to memory as well as totalized
for 24 hour periods with a Summation icon (DailyBTU) and stored
Logger Initated Alarming:
As a separate function integral to the logger, incoming data
or any calculated can be utilized as a condition for an alarm.
Upon detection of an alarm condition, a numeric page(s) can
be generated, local alarm control outputs (relays and TTL
signals) can be cycled and/or local messages can be written
to the logger display.
So, in the case of this program an
alarm condition could be included just after the hourly BTU
integration icon to check for a minimum hourly BTU production.
If the minimum is not met an alarm would so indicate.
With standardized “off-the-shelf”
Logic Beach data logging instruments a fairly simple BTU monitoring
system can be implemented. The downloading of the data could
be automated by way of HyperWare Automation Program (HAP).
HAP can be programmed to automatically poll the data logger
on a user-defined schedule, produce regular reports via a
printout and receive and alert the operators to alarms via
a pop-up text window initiated by the data logger.