Chalmers University of Technology Invoice Service SE-412 96 Gothenburg Sweden
Phone (switchboard) +46 31 772 1000 www.chalmers.se
Determine the temperature efficiency of heat recovery System RG 5400
Commissioned:
Regenair Scandinavia Erik Larsson Radiovägen 2 13526 Tyresö Box 680 SE -Sweden-
Measured object: Heat recovery systems Regenair Scandinavia RG 5400 installed in an office building SSPA, Chalmers University of Technology.
Nominal airflow 5400 m³/h Control and regulation carried out in equipment from the same company.
Measurement period 2: March-2005
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Chalmers University of Technology Invoice Service SE-412 96 Gothenburg Sweden
Phone (switchboard) +46 31 772 1000 www.chalmers.se
Abstract
The Contract involves the measurement of the air temperature, determining the temperature efficiency of the heat recovery system (described below) and the control survey of the air flow for the temperature measurement. This work has been performed by Tommy Sundström and Lars Ekborg CIT Energy Management AB on behalf of Ola Wiehager, Regenair Scandinavia.
While measured, the air flow was on both sides (supply and exhaust air) approx. 4600 m³/h. Temperature efficiency on the supply air side was up to 90% (fan effect considered in calculation). The corresponding value, when supply air heat is excluded, was 82%. Comparing to the measurement results from 21/06/1989 the efficiency with the fan effect was 95% and without 89%.
Measured object: Heat recovery systems Regenair Scandinavia RG 5400 installed in an office building SSPA, Chalmers University of Technology. The System normal air flow is about 5400 m³/h and as such it got installed year 87/88. The aggregate has thus diversified its operation slightly over the 17 years.
A typical Regenair Scandinavia Unit contains 2 energy cores (A & B), special change over damper section, an exhaust fan, and a supply fan. When energy recovery is called for, the dampers position so that Energy Core A will add energy to the supply air stream, heating up the air. Simultaneously Energy Core B is absorbing energy from the exhaust air stream. After 60 seconds, the dampers reposition. Now Energy Core B is adding the energy it reclaimed in Phase 1 to the supply air stream, heating it up. Simultaneously Energy Core A is “recharging” by absorbing energy from the exhaust air stream. This sequence will be repeated every 60 seconds.
Measurement methods and instruments Temperature recording performed with thermocouples (Type Swema Air 300) with a sensor Model SWA 31 (Serial Number: 382989, calibrated 2004-05-27). The maximal error of measurement according to the manufacture is ±0, 3 °C. The Temperature was also measured with an instrument Model Dostmann P650 (Serial Number: 65003110141, calibrated 2004-09-07). The maximal error of measurement according to the manufacture is ±0, 02 °C. Page | 2
Chalmers University of Technology Invoice Service SE-412 96 Gothenburg Sweden
Phone (switchboard) +46 31 772 1000 www.chalmers.se
The air pressure was measured with four fixed installed instrument Model Stifab CRM-040. Two of the instruments are sitting in the Supply Air duct and the other two directly connected to the aggregate. Basic k-factor is 96, 6 [m2K].
Pressure difference between the measuring points is measured with an instrument model Swema Air 300, with the sensor model SWA 10 (Serial Number: 362309 calibrated 2004-05-27). The maximal error of measurement according to the manufacture is ±1% or ± 0, 3 Pa.
Measurement period: The measurement was the 28 February 2005 with an outside temperature of ± 0°C.
Results: Below you will find a summary of the results including the Air Flow, the pressure and the measured temperature:
Table 1: Measured Air Flow:
Position
appliance's name
Pressure difference (pa)
Air flow (m³/s)
MP3a
45,2
2315
MP1
45,0
2308
Total
-
4623
MP3b
43,6
2272
MP2
47,2
2365
Total
-
4637
Supply duct
Exhaust ducht
Temperature Measurement: The outside temperature during the measurement was in average of – 0, 3°C. At the start it was -0, 5°C and at the end +0, 1°C. Exhaust Air temperature before the fan was 20, 7 °C.
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Chalmers University of Technology Invoice Service SE-412 96 Gothenburg Sweden
Phone (switchboard) +46 31 772 1000 www.chalmers.se
Temperature in supply air after the fan:
These measurements were taken with the described instrument above type Swema air. The measurements were taken during 2 minute with 1 measurement per second. The measurement was repeated twice.
First Measurement: Average temperature:
18, 6 °C
Maximum temperature:
19, 9 °C
Minimum temperature:
16, 4 °C
Deviation:
0, 96 °C
Second Measurement: Average temperature:
18, 5 °C
Maximum temperature:
20, 0 °C
Minimum temperature:
16, 1 °C
Deviation:
0, 96 °C
Temperature in supply air before the fan:
this temperature was measured to estimate the temperature efficiency exclusive the temperature increase caused by the inlet fan. The measurement was made with the above-described type of instrument Dostman. The estimated average temperature was about 17 °C.
Temperature Efficiency: The temperature efficiency is made up of:
[%]
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Chalmers University of Technology Invoice Service SE-412 96 Gothenburg Sweden
Phone (switchboard) +46 31 772 1000 www.chalmers.se
Temperature efficiency exclusive the temperature increase caused by the inlet fan:
Temperature efficiency inclusive the temperature increase caused by the inlet fan:
Gรถteborg 2005-03-11
Lars Ekberg CIT Energy Management AB
Tommy Sundstrรถm CIT Energy Management AB
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