Influence of load mass, drum speed and load composition on evenness of drying in a heat pump tumble dryer

Figures & data

Figure 1. Simplified drum cross section with main dimensions in millimeters.

Figure 2. Schematic of the heat pump tumble dryer with locations of sensors.

Table 1. Fabric characteristics.

	Bed sheets	Pillowcases	Towels
Mass per unit area (g/m^2)	185 ± 10		220 ± 10
Length (mm)	2400 ± 150	800 ± 50	1000 ± 50
Width (mm)	1600 ± 40	800 ± 20	500 ± 30
Weight per piece (g)	725 ± 15	240 ± 5	110 ± 3

Table 2. Test load composition.

Mass load, c (kg)	Number of items, Ni
	Bed sheets	Pillowcases	Towels
2	0	4	9
4	2	4	14
6	2	8	24

Figure 3. Variability of initial and final moisture content of each fabric item in the test run at 2 kg load and 58 rpm drum speed (T – towels, P – pillowcases, horizontal red line – nominal moisture contents for complete load).

Table 3. Measured operating points.

	Low	Intermediate	High
Drum speed, n (rpm)	36	47	58
Load mass, c (kg)	2	4	6

Figure 4. (a) Energy efficiency and (b) specific drying time as a function of drum speed and load mass.

Figure 5. Measured evenness of drying with models, specific to each load mass.

Figure 6. Measured and modeled evenness of drying.

Figure 7. Modeled evenness of drying.

Figure 8. Histograms of deviation of evaporated water share for all operating conditions.

Figure 9. Mean absolute deviation of evaporated water share for different item types.