System Overview:

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 to memory.

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.

Conclusion:

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.

 

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