JPS61184361A - Air-cooled heat pump turbo chiller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a heat pump type air-cooled centrifugal refrigerator,
Especially regarding the performance of air-cooled evaporators during heating.

[Background of the invention]

Conventional air-cooled evaporators are mainly arranged horizontally, and in that case, even if refrigerant liquid accumulates in the evaporator tube, the refrigerant liquid is entrained by the gas due to the gas flow rate inside the tube, and the refrigerant liquid accumulates to the extent that the heat transfer area is greatly reduced. However, as the refrigeration capacity increases, the required heat transfer area increases significantly, so if the evaporator is placed horizontally, the installation area also increases significantly.

In order to reduce this, air-cooled heat exchangers have been used vertically, and as a result, refrigerant mist inevitably accumulates inside the heat transfer tubes below, reducing the effective heat transfer area and reducing performance. A pump etc. was installed to pump out the refrigerant liquid and return it to the condenser. This method requires less installation space.

If you compare it with the horizontal arrangement of air-cooled heat exchangers.

However, the addition of the refrigerant pump and liquid level control functions requires extra electricity, and there are more moving parts and the pump frequently starts and stops due to liquid level control, which can easily cause problems. there were.

[Purpose of the invention]

The purpose of the present invention is to add a simple heat exchanger without adding mechanical parts such as a pump, thereby creating a pool of refrigerant in the heat transfer tube at the bottom of the vertically arranged air-cooled evaporator.
The purpose is to prevent performance deterioration from occurring.

[Summary of the invention]

In air-cooled heat pump centrifugal chillers, the air heat exchanger is used as a condenser for cooling and as an evaporator for heating. During heating, superheat is controlled by the expansion valve, so almost no refrigerant liquid should remain.However, if the air heat exchanger is arranged vertically, the position of the head means that refrigerant liquid will inevitably accumulate in the heat transfer tubes at the bottom. It was discovered that the performance of air heat exchangers deteriorated. Therefore, the above-mentioned problem is solved by using condensed refrigerant having a relatively high temperature to evaporate the refrigerant liquid accumulated in the evaporator.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

As shown in Fig. 1, electric valve switching is performed in a turbo chiller consisting of a compressor 1, air heat exchanger 2, water heat exchanger 3, intercooler 4, accumulator 5, piping connecting each device, and electric valves. A heat pump system is installed to provide cooling in the summer and heating in the winter. In summer, air heat exchanger 2 is a condenser and water heat exchanger 3 is an evaporator (cold water generator); in winter, air heat exchanger 2 is an evaporator and water heat exchanger 3 is a condenser (hot water generator). functions as

During heating, the mist of the refrigerant gas evaporated from the air heat exchanger 2 is introduced into the accumulator 5, and only the refrigerant gas is sucked into the compressor 1. The refrigerant gas pressurized by the compressor 1 enters the water heat exchanger 3 and is condensed to generate hot water for heating. The condensed refrigerant liquid enters the intercooler 4, where some of the refrigerant evaporates and is sucked into the second stage of the compressor 1. The remaining liquid is blown out to each tube of the air heat exchanger 2 via the expansion valve 6. Ten expansion valves 6 are attached to each air heat exchanger 2, and the number of activated expansion valves is changed depending on the load to control the heating capacity. The refrigerant blown into the tube of the air heat exchanger 2 is heated by the air heat exchanger and evaporates.
A small amount of the refrigerant remains in liquid form. A part of it flows into the accumulator 5 together with the refrigerant gas, but a part remains in the lower part of the air heat exchanger.

Therefore, the bottoms of the left and right outlet headers 7.8 of the air heat exchanger 2 are connected, and a condensed refrigerant liquid pipe is passed therethrough, thereby heating and evaporating the remaining refrigerant liquid that has not completely evaporated. The refrigerant liquid has a temperature of about 5°C, and evaporates due to the temperature difference. The required heat transfer area is determined in proportion to the amount of refrigerant that accumulates, and the length of the piping described above may be determined accordingly.

In this example, the 3-inch pipe has a heat transfer area of 2 m in length.

According to this embodiment, during heating operation, the tubes of the air heat exchanger are arranged vertically to reduce the installation area, but the refrigerant liquid accumulates in the tubes at the bottom of the air heat exchanger, which deteriorates the performance of the air heat exchanger. You can drive without any problems.

In addition, in Fig. 1, the white arrow indicates the time of cooling.

The black arrows indicate the flow during heating.

〔Effect of the invention〕

As described above, according to the present invention, during heating in an air-cooled heat pump centrifugal chiller in which air heat exchangers are arranged vertically, the refrigerant liquid that accumulates at the bottom of the air heat exchanger can be heated and evaporated by the condensed refrigerant liquid. Therefore, heating operation of the air-cooled heat pump centrifugal chiller can be performed without deteriorating the performance of the air heat exchanger.

[Brief explanation of drawings]

Fig. 1 is a flow sheet of an air-cooled heat pump centrifugal chiller according to an embodiment of the present invention, Fig. 2 is a plan view of a heat exchanger attached to a part of the bed of the air heat exchanger, and Fig. 3 is its flow sheet. It is a front view. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Air heat exchanger, 3... Water heat exchanger, 4... Intercooler, 5... Accumulator, 6... Expansion valve, 7,8... ... Derobetsuda. 1st concave → 111 prolate jaw Z mouth 3 fig.

Claims (1)

[Claims] In a heat pump refrigeration cycle, in which an air-cooled heat exchanger is used as an air-cooled condenser for summer cooling and as an air-cooled evaporator for winter heating, the difference between high-temperature refrigerant liquid in the evaporator and refrigerant liquid accumulated in the evaporator during winter heating is An air-cooled heat pump centrifugal chiller characterized by having an auxiliary heat exchanger installed between the two.