Measurement data of an air-to-air membrane enthalpy and a heat exchanger

The data presented in this article are the measurement results of an air-to-air enthalpy exchanger and a heat exchanger. Such exchangers are used in ventilation devices. The data include 86 measurement points with different boundary conditions (winter and summer condition). The temperature, the humidity, the volume flow and all relevant pressures and pressure differences are provided. The data are mean values of a steady-state measurement. For more insight and interpretation of the results please see “Effectiveness of a membrane enthalpy heat exchanger” [1].


Data
The data presented in this article were acquired in the ventilation test rig of the University of Innsbruck. The characteristics of a heat and an enthalpy exchanger, shown in Fig. 1, were measured for different boundary conditions. Altogether 104 steady-state measurement data points could be arrived, which include a temperature range between À7 C and þ30 C for different relative humidities. The detailed boundary conditions can be found in the section Boundary conditions.
The data set includes two tables with the raw data of the steady-state results of the experiment (see section Experimental set-up for the description of the variables). The data set is separated for the heat exchanger and enthalpy exchanger. Each data point represents a steady state result that is a mean value over 30 min. For at least another 20 min before starting the measurement the standard deviation of the temperatures had to be smaller than ±0:05 C. DOI  In addition, the data of the equivalent air layer thickness of the enthalpy exchanger's membrane can be found as figure in the data (see Fig. 2). The experimental set-up for the determination of these data can be found in Ref. [1] (see Fig. 3). The data can be used to validate models of enthalpy and/or heat exchangers with different detail levels (1D, 2D or 3D). The boundary conditions used during the measurements can be usually expected in the temperate climate zone. With this data the influence on an overall system (i.e. a ventilation unit) using an enthalpy exchanger could be obtained. This refers to single effectiveness parameters (such as temperature, humidity, enthalpy), but also to system performance parameters (such as coefficient of performance) including the pressure drop over the heat and enthalpy exchanger. The data set includes 104 steady-state measurement points without inter-or extrapolation. They show the full behavior of the exchangers in a wide range. Prediction of the frost risk of both types of exchangers could be carried out. By means of building simulation the impact on the indoor air quality could be shown by directly comparing heat and enthalpy exchanger. New control strategies (i.e. for humidification or de-humidification purposes) could be achieved.  ventilators. The pipes are connected to two climate chambers (not shown here). One climate chamber emulates the room air and the second one emulates the ambient air. Both climate chambers can be controlled with respect to temperature (heating and cooling) and moisture (humidification and dehumidification). The heat exchanger was situated in a third room with a constant room temperature (equal to the extract air temperature of the heat exchanger). The temperature at the inlets can be kept constant within ±0:05 C and the relative humidity can be maintained within ±2:0% during a measurement cycle. For both air streams, the conditions at the inlet and outlet are measured. The temperature is measured near the inlet to the heat exchanger with five temperature sensors (w). Additionally, the relative humidity (4) and the temperature are measured within a short distance (to ensure uniform air properties by the mixing of the air). The volume flow _ V is measured with orifice plates and differential pressure indicators. Depending on the range of the expected volume flow, different orifice plates are used. Oversized running-in sections guarantee a uniform flow. In addition the differential pressure (Dp) between the inlets and outlets of the heat exchanger was measured.  All air ducts used to connect the ventilation unit to the test rig were insulated with a 13 cm thick layer (Armaflex and rock wool) including all pipes and the volume flow measurement. The exchanger unit itself was packed in a polystyrene case (approx. 2.5 cm thickness) with additional 3 cm of insulation. Table 1 shows the measurement devices used and the accuracies that can be achieved for each of it. The measurement inaccuracy cannot be assumed to be constant therefore for the whole data set the inaccuracies are additionally provided.

Calibration and measurement inaccuracy
The calibration of the temperature sensors (Pt100 and thermocouple) is done with an internal calibration equipment based on a calibration bath and two reference sensors (Dostmann T4200 and Burster KELVIMAT 4306) which itself are calibrated according to ISO standards. The calibration was done in a temperature range of À10 Ce50 C with 1 K steps.
The calibration of the humidity sensors is done with a humidity calibrator (Michell Instruments HygroCal100) and a dew point mirror (Michell Instruments Optidew) as reference. The calibration was done between 10% and 90% relative humidity (in steps of 10%) at a room temperature of around 5 C, 15 C and 25 C.
For the calibration of the volume flow a W € OHLER DP 700 is used. It uses a laminar flow element and a hot-film anemometer. The calibration was done for a temperature range of the air flow between 5 C and 35 C. Table 2 and Table 3 show the boundary conditions during the measurement, which are typically winter and summer conditions called.

Used efficiency parameters
For evaluating heat and enthalpy exchangers the method of effectiveness (for temperature and moisture) is used (compare (1) to (4)). Please be aware of the measurement uncertainties, especially in case of using h x .