During on-site operation and maintenance, it is not uncommon for the outlet temperature of hot and cold heat exchangers to fail to reach the set value. Investigation often reveals that one common cause is an undersized heat exchange area estimated based on experience; conversely, an oversized area increases investment and footprint. When selecting a model, procurement personnel need to reasonably determine the heat exchange area and margin based on the load fluctuation range and control valve characteristics.
A: The heat exchange area should be calculated based on the heat transfer duty under design conditions, the log mean temperature difference, and the heat transfer coefficient, and should not be estimated solely by experience. An undersized area will prevent the outlet temperature from reaching the set value; an oversized area will increase equipment investment and footprint. It is recommended to verify the calculation against operating data from similar conditions.
A: If the margin is too small, the outlet temperature is prone to fluctuate with load changes; if the margin is too large, the control valve opening will be too small under low-load conditions, degrading the pressure drop characteristics. Generally, a margin of 10%–20% can be retained on top of the calculated area, and verified against seasonal load variations and the control valve characteristic curve.
A: The inlet and outlet temperatures, flow rates, allowable pressure drop, medium properties, and installation space for both the hot side and cold side must be specified. It is also recommended to record inlet and outlet temperature and pressure data across different seasons to provide a basis for subsequent selection adjustments. The HRS-550 hot and cold heat exchanger can be sized and calculated based on the above parameters, and the connection orientation and installation method can be configured according to site conditions.
A: Before procurement, the differences between design conditions and operating conditions should be verified, and the matching relationship between the control valve adjustable range and the heat exchanger margin should be confirmed. For applications with large load variations, a variable-condition calculation report may be requested. After the equipment arrives, check whether the nameplate parameters match the order requirements, and retain operating data for subsequent evaluation.
