RU2548324C1 - Berry drying heat pump unit - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: in a heat pump unit a provision is made for the simultaneous control of the temperature of a drying agent and the temperature of shelves of the shelf stand, on which berries (product) being dried are located. The drying agent temperature control is performed due to the connection to the composition of a cooling machine of an external capacitor parallel to an internal capacitor and a temperature sensor installed at the internal capacitor drying agent outlet. Shelves temperature control is performed due to the introduction of a utilisation heat exchanger for heating of an intermediate heat carrier, a three-way valve at the shelf stand heat carrier inlet and the temperature sensor at the shelf stand heat carrier inlet. The invention shall provide for the enhancement of the technological drying process due to the simultaneous temperature control of the drying agent and berries during the drying process.

EFFECT: reducing the time required for berry drying.

1 dwg

Description

The invention relates to refrigeration, and more specifically to heat pump units, and can be used for drying berries.

Known heat pump dryer mainly for drying food products, containing a compressor refrigeration machine and a closed loop circulation of a drying agent, in which a fan, a chiller of liquid refrigerant, a condenser of a chilling machine, a drying chamber, a cooler of a drying agent, an evaporator of a chilling machine and a moisture separator are installed [1] .

The disadvantage of this installation is the relatively low quality of the process due to the inability to control and maintain the temperature and humidity of the drying agent in the required limits.

As a prototype, a heat pump dryer for drying fish dried by the design closest to the one proposed, consisting of a compressor, two condensers (internal and external), an air cooler, a linear receiver, a direct drying chamber and a fan, was selected [2]. The drying agent sequentially passes the air cooler and condenser, which operates alternately with a condenser located on the street. The installation selected for the prototype allows you to adjust the temperature of the drying agent due to the fact that it includes internal and external condensers and by passing hot vapors to the suction side, increase the temperature of the evaporator to a temperature above the dew point temperature, reducing the drying intensity.

The disadvantage of this installation is the supply of heat to the material to be dried only from the drying agent and, as a result, the longer process time. While the drying intensity is determined not only by the parameters of the drying agent, but also by the method and amount of heat supplied to the product.

The technical result is the acceleration of the drying process due to the simultaneous control of the temperature of the drying agent and berries in the drying process.

The technical result is achieved in that in a heat pump installation for drying berries containing a compressor refrigeration machine and a drying chamber, in which there are racks with shelves in which channels for the passage of the heat carrier are arranged, according to the invention, a heat exchanger is connected in front of the internal condenser of the refrigeration machine to recover heat the coolant used to heat the shelves of the rack, and a three-way valve for regulating the intensity of heating of the shelves using a temperature sensor.

The temperature of the intermediate coolant is changed according to a predetermined program using a three-way valve, while the temperature of the drying agent and the intermediate coolant are regulated.

The drawing schematically shows the proposed heat pump installation for drying berries (Fig. 1).

The heat pump installation for drying berries contains a refrigerator with a compressor 1, a heat exchanger 2, an internal condenser 3, an external condenser 4, a linear receiver 5, a filter drier 6, a thermostatic valve 7, an air cooler 8, and solenoid valves 9; 10, check valves 11; 12, an expansion tank 13, a pump 14, a three-way valve 15, a rack with internal channels in the shelves 16, on which the material to be dried is located, temperature sensors 17; 18, the camera body 19, in which the partition 20 is arranged.

Installation works as follows.

A drying agent with a temperature that is regulated by the alternate inclusion of condensers 3 and 4 in the operation, drains the berries (product) located in the baking sheets on the rack. Next, the moistened drying agent is dried, passing through the air cooler 8, due to the fact that the temperature of the heat exchange surface of the air cooler has a temperature below the dew point temperature. Condensed moisture is collected in a pallet and removed through a water trap into the sewer. Then the drying agent is heated due to the higher temperature of the condenser 3. In this case, the temperature of the drying agent rises, and the moisture content remains constant. When the set temperature of the drying agent is reached, the temperature sensor 17 receives signals to the solenoid valves 9 and 10 - the solenoid valve 9 closes and the solenoid valve 10 opens and the temperature of the drying agent stops rising. The temperature of the drying agent in the entire chamber 19 begins to decrease and, having reached the set temperature, the solenoid valve 10 is turned off and the solenoid valve 9 is turned on and the temperature in the chamber 19 begins to rise again. Thus, the temperature in the chamber with a differential of 1-2 ° C is maintained. The intermediate heat carrier is heated in the heat exchanger 2 and pump 14 is fed into the rack with shelves 16, inside which channels are arranged for the passage of the intermediate heat carrier. By means of the temperature sensor 18, the temperature of the coolant at the outlet of the rack (at the inlet to the heat exchanger 2) is maintained at least 5 ° C above the temperature in the chamber to prevent liquid refrigerant from entering the condenser.

The circulation of the drying agent occurs due to the fans of the air cooler 8 and the internal condenser 3. The uniformity of the flow of the drying agent is provided by the partition 20.

Regulation of the temperature difference between the temperature of the shelves of the rack 16 and the temperature of the drying agent is a distinctive feature of the proposed heat pump installation. Using the heat of the superheated steam leaving the compressor 1 allows you to set the temperature of the berries above the temperature of the drying agent due to the supply of heat from the intermediate heat carrier through the surface of the shelves. The moistened drying agent from the berries is dried, passing through the heat exchange surface 8, since the temperature of the heat exchange surface of the air cooler is lower than the dew point temperature.

The temperature of the intermediate coolant at the outlet of the heat exchanger is regulated by a temperature sensor 18 installed at the outlet of the rack 16. When the coolant temperature becomes lower than the set temperature, a signal is sent to the three-way valve 15. When the three-way valve is opened, the coolant with a higher temperature will mix with the cooled coolant, and the temperature coolant will begin to rise. When the temperature of the coolant rises above the installed three-way valve starts to close.

In the proposed heat pump installation, by introducing a heat recovery heat exchanger and a three-way valve, it is possible to maintain the temperature difference between the dried product and the drying agent, which reduces the drying time of the product, ensures a uniform drying process throughout the rack and obtain a product with high quality indicators.

Sources of literature

1. A.S. No. 1038756 USSR, F25B 29/00. Heat pump dryer / Dvornikov A.F. - No. 3349342/23 - 06; declared 10/22/81; publ. 08/30/83, bull. No. 32 (analogue).

2. Patent No. 2372781 of the Russian Federation, A23B 4/03. Heat pump installation for drying fish / Raschepkin A.N., Ermolaev V.A., Raschepkina E.A. - No. 2008100840/13; declared 07/20/2009; publ. 11/20/2009.

Claims (1)

A heat pump installation for drying a berry, comprising a compressor refrigeration machine and a drying chamber with a rack with shelves located in it, in which channels for the passage of coolant are arranged, characterized in that a heat exchanger is included in the circuit of the chiller in front of the internal condenser for heat recovery, used for the heat transfer medium used for heating shelves of the rack, and a three-way valve for regulating the intensity of heating shelves using a temperature sensor.