FI104743B - Drying apparatus for textiles - Google Patents

Description

104743

The present invention relates to a drying apparatus for textiles, such as a tumble dryer or a drying cabinet having a drying space for wet textiles, an air inlet connected to a drying space for bringing warm dry air to this space, a dehumidification connected to the drier 10. to remove the warm moist air therefrom, the fan means for providing airflow through the drying space in a closed circuit comprising means for condensing moisture from the warm humidified air stream and means for heating the dehumidified air, the condensing means being a heat pump condenser pump

In the case of tumble dryers and drying cabinets in which a stream of air 20 is passed through a drying space in a closed circuit, it is known to utilize the heat-binding part of the heat pump for drying; to dehumidify the warm moist air coming from the room; and

• similarly utilizes the heat pump heating part I

'to heat the drier air thus obtained, which after this: ...: 25 is taken to the drying chamber.

• * • · · f ··· In a heat pump, which is monitored as a closed system, 2 there is always an excess energy corresponding to the compressor: energy. In order to avoid too high pressure temperature levels on the • condenser side, the heat pump requires some type of control. This can be in the form of heat losses • · · ·· "in the form of ambient walls in combination with 9 9 9 - some type of pressure temperature detection. It can often be advantageous to control these heat losses and even increase them if necessary, especially

• I

104743 2 if losses can be recovered.

To increase the power of the heater, thereby shortening the drying times, the heat pump system and the 5 compressors used herein can be dimensioned to provide a power significantly higher than the loss-limiting wall surfaces. If the pressure and temperature are then controlled in the system, a lower drying capacity is obtained. Therefore, it is necessary instead to apply an additional load 10, which can be suitably controlled so as to provide suitable drying conditions.

It is thus an object of the invention to provide a drying device which provides efficient drying in a short time without excess heat generated by the heat pump compressor causing ever rising temperature levels in the heat pump cooling medium circuit which on the one hand degrades the drying effect and on the other hand increases the compressor temperature. Said task is accomplished by 20 imaging devices having the characteristics of the characterizing part of claim 1. Preferred embodiments of the invention will be apparent from the dependent claims.

Other advantages of the invention will be apparent from the description referring to the accompanying drawings, in which: Fig. 1 schematically illustrates the construction of a drying * * * device according to the invention, and Fig. 2 shows a schematic diagram of the pressure of the enthalpy of the cooling medium. function using simple] · | · φ30 curves for a given circuit.

• · • ·

Figure 1 schematically illustrates a drying apparatus 10 comprising a drying space 11 having an air inlet 12 and a deaeration 13. The wet clothes to be dried are arranged in a drying closure closed by an unimproved door or the like. 3. The air flow through the drying space is forced to pass through a closed system which, in addition to the drying space 11, includes a fan 14, an inlet duct 15 and an exhaust duct 16. The fan is disposed in a conduit 17 which connects the inlet and outlet ducts 5 to the supply air conduit 15. 18, and the heat recovery portion of the heat pump system, i.e. the evaporator 20, is disposed in the exhaust air conduit 16. Conventionally, the air portion of the condenser is connected via a coolant medium conduit 21 to a compressor 22 which supplies the heat pump system. a non-return valve 24 which separates, in terms of pressure, the high pressure part of the heat pump system from its low pressure part 15. Conduit 25 connects the expansion valve to inlet portion of evaporator 20, and conduit 26 connects evaporator outlet to compressor 22.

In a closed circuit, where the air flow is flowing in the direction of the arrows 27, 28 20, there is an exhaust duct upstream of the evaporator 20. a heat exchanger 29 of the air / air type fitted schematically in Fig. 16 and shown schematically in cross-flow: · ;;; a diverter. The air coming from the drying space 11 is cooled in the heat exchanger 29 by the air taken from the space where the drying apparatus 10 is ... ... 25, and for this purpose the fan 30 is arranged to suck air through the inlet conduit 31: the air thus heated is returned to the space .j. or rather it is used to heat another space

MM

. •; \ 30 si. In the latter case, the intake air of the fan 30 • · · # is supplied from the space to be heated, whereby this space is • · · * · * · 'connected to the space where the dryer is located through suitable: ... ... ducts or the like.

For example, the drying apparatus shown in Figure 1 may be a drying cabinet or drying cabinet, in which the drying function is substantially similar in both cases. At the drying cabinet, the clothes to be dried are arranged to hang in the cabinet, and a warm air stream is forced through 5 cabinets to warm the garments and thereby dry them. The released moisture is trapped in the flowing air and condensed upon contact with the heat pump evaporator 20. In the tumble dryer, the garments are fitted to a rotating drum which is rotatably used while forcing a warm air stream through the drum. In both cases, drying is continued until the garments are completely dry or until they have reached a degree of dryness suitable for, for example, mangling.

Figure 2 illustrates the function of the heat pump, which schematically shows a pressure / enthalpy diagram of a suitable refrigerant medium of the freon type. The pressure is shown on the vertical axis and the enthalpy value on the horizontal axis. The diagram has a curve having two portions 33 and 34, both of which extend obliquely from left to right.

Both parts of the curve delimit the areas in the graph where

• I

the cooling medium is in a different state. Left curve-

III

on the left side of section 33, the cooling medium is liquid

• I I

V ', between the two curve sections 33 and 34, the cooling medium is partially liquid, partially gaseous, and ..] · * to the right of the right portion of the curve, the cooling medium is in the gas space. In the diagram is placed a trapezoidal shape. The corners of the image are represented by reference numerals A, B, C, and D. The function of the heat pump can be described by means of the figure showing a simple saturated cooling cycle. This corresponds to the theoretical • »·. '·! and requires the refrigerant medium in the vapor space to exit the evaporator 20 and enter the compressor 22 as saturated vapor at the time of vaporization. At a constant temperature and pressure, and further that the cooling medium in liquid form exits the condenser 18 and enters the expansion valve 24 as a saturated liquid, such as at ambient temperature and pressure during condensation of the cooling medium. Although the working cycle in a real heat pump differs slightly from the theoretical case, this may well illustrate the way the heat pump works. j

Point A in the diagram represents the thermal medium at position 10 after the condenser 18 where the condensation process is completed and the medium is a saturated liquid having a condensation pressure and temperature. On the way to the expansion valve, it is assumed that there is no change in the state of the fluid, and as the fluid then passes through the valve, expansion and pressure drop from the condensation pressure to the vapor pressure occurs. This is shown between A and B, which is vertical in the diagram, and shows that the pressure drop occurs adiabatically, i.e. without changing the enthalpy value. Assume that the expansion occurs without the addition of “20 heat or loss of heat, and without work being performed.

«I

«I I

The next part of the cycle consists of the cooling medium

• f I

evaporation in the evaporator 20. Evaporation occurs at 25 constant temperatures and pressures, which means that

the steam associated with the sea buckthorn moves from point · B to point C in the diagram along the horizontal line. Point B

the medium is both liquid and gas, while ··· on the other hand, at point C, the medium has completely transitioned to · · · · 30 gas space. At point C, the medium is an overheated /, vapor with a vapor pressure of · · m * ·. As shown in the diagram, the heat content or enthalpy value of the tool increases with evaporation as it binds heat from the exhaust air duct 16 * *. : 35 flowing air.

• · · • · 6 104743

The third step of the work cycle is shown in the diagram C-D, which corresponds to the increase in pressure occurring in the gaseous medium by the action of the compressor 22. Energy is introduced into the tool between points C and D, which corresponds to the mechanical work performed by the compressor. At point D, the working medium has a state of superheated steam, which means that its temperature is higher than the saturation temperature corresponding to the pressure. Before the vapor can condense, the excess temperature must be eliminated and the thermal state reduced to the vapor pressure.

The latter temperature reduction takes place in the condenser and corresponds to the interval D-E of the diagram.

The last and fourth steps of the work cycle consist of the condensation of the medium vapor in the condenser 18, which corresponds to the interval E-A in the diagram. In the same way as evaporation, condensation occurs at constant pressure and at a temperature corresponding to the horizontal line in the diagram. During condensation, heat is supplied to the flowing air in the supply air duct 15, and at point A all the media gas is condensed · Point A is to the left of line 33! side, which means that the thus formed ;;; a certain undercooling of the coolant has occurred. This is of importance for the expansion valve function • · '••• '25 and is thus guaranteed to function in pure liquid, * 1' without mixing gas.

«» I ♦ · «« · «

As shown in the diagram in Figure 2, the line B-C is shorter ··· than the line D-A, which means that the heat supplied to the drying air stream * · * j 30 is continuously present. *. greater than the heat removed from the air flow from the exhaust duct 16 »· · ** # | *. This means that the temperature of the drying system is constantly increasing, which can cause: • Y: the risk that an elevated temperature will impair the operation of the heat pump system in terms of condensing capacity, • and also a risk of overheating of the compressor. To solve the problem, an additional load is fitted to the exhaust air flow in the form of an air-to-air heat exchanger, which is capable of transporting excess heat energy. This is carried by the air stream provided by the fan 30 and passed through conductors 31 and 32 in the heat exchanger, and can be further introduced into the space in which the drying device is located. If the space is too small to recover this thermal energy, the heat exchanger can be connected to another 10 space which can be heated with this air.

As mentioned at the outset, it may be advantageous to control the excess load, and for this purpose a pressure detector 35 is fitted which senses the pressure in the pressure medium of the condenser 18. Because pressure and temperature are interdependent, pressure is also a measure of temperature. The pressure detector is coupled to a control device 36 which enables the fan 30 to be turned on and off.

In this way, the pressure and thus the temperature can be maintained at the desired level in the heat pump system so that the extra load in the form of an air / air heat exchanger 29 is switched on as the pressure increases.

•? In the embodiment shown, 25 air / air heat exchangers are used as an additional load. This is optimal for energy. However, the additional load may also be, for example, a water-cooled extra condenser where energy can be removed from the cooling water by suitable means. 1: 1.30 for heating hot water.

i · »*» -% «=»> i • · · • «« «• · 9 a 9 a a» 4 · • I · V · · «• · • •« * ·

Claims (7)

A textile dryer such as a dryer or a drying cup including a wet-drying chamber (11). textiles, an air inlet (15) connected to the drying chamber • · · * (11) for supplying hot dry air to this likewise an air outlet (16) connected to the drying chamber (11) for removal of hot moist air from this, fan means (14) for driving an air stream through the drying chamber (11). in a closed circuit comprising means (20) for condensing moisture from the hot humid air stream as well as. means (18) for heating the thus dehumidified air, the condensing means (20) being the extender in a compressor driven heat pump system (19) and the heating means (18) is constituted by the condenser in the heat pump system, characterized in that an additional temperature-lowering load (29) is arranged between the air outlet (16) and the exchanger (20) in the heat pump system (19) which in the closed circuit, remove an amount of energy corresponding to the part of the energy supplied by the compressor (22) that is not consumed in the drying process. 10 Drying apparatus according to claim 1, characterized in that the additional temperature-lowering load (29) is of variable size and / or variable switch-on time. 15 Drying apparatus according to claim 2, characterized in that the size of the respective switch-on time for the additional temperature-lowering load is arranged to be controlled in dependence on the temperature of the heat pump condenser 20 (18). 4. Drying apparatus according to any preceding claim,. characterized in that the further temperature-lowering load (29) is an air / air heat exchanger, which is adapted to cool the warm humid air with air from the environment of the dryer. The dryer according to claim 4, characterized in that the air-to-air heat exchanger (29) comprises a fan (30) which drives cooling air from the environment of the dryer through the heat exchanger (29), wherein means (35) are arranged to sense. ·,: the temperature or pressure in the condenser (18) of the heat pump to create a parameter intended to control switching on. respective fractions of the fan (30). «· * * * ·. · * 35 9 · · f • · · • 104743 11 6. Drying apparatus according to claim 4 or 5, characterized in that the air-to-air heat exchanger circuit is connected to a room from the room where the drying apparatus is arranged in a separate room by means of suitable lines. 5 Drying apparatus according to any one of claims 1-3, characterized in that the temperature-lowering load consists of a water-cooled condenser. «» »* ~ • · I t · ft ft • · I» · • · · • «· ·« · · • ♦ «• * ·« · 1 • ft • ft »-. · · · • t · • ft 9 9 I * * ft ft ft • ft _ ft ft - ft ft * ft ft ft ft ft · ft ft ft ft ft ft ft ft ft ·