冬場の冷凍設備の運転トラブルとその対策

Operation problems and Countermeasures of refrigeration equipment in winter

In Winter, when the outdoor temperature is wet and low, and the condensation pressure has a great influence on the performance of the refrigeration system.

When the condensation pressure (or condensation temperature) is high, the compression ratio increases.

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And the volumetric efficiency of the compressor decreases, resulting in the reduction of refrigeration capacity and the increase of power consumption. The higher the exhaust temperature and the higher the condensation pressure, the greater the adverse effect.

The phenomenon of high condensation pressure mainly occurs in Summer. At this time, the condensation pressure should be reduced as much as possible to ensure the economy and reliability of the system operation.

However, in winter, the condensation pressure of refrigeration equipment may be too low。

When the condensing pressure is too low, the pressure difference between the front and back of the expansion valve is too small, and the capacity of the expansion valve is reduced, resulting in the insufficient liquid supply capacity of the system refrigerant, the lack of liquid in the evaporator, and the refrigeration capacity of the system is greatly reduced, and the unit is protected under low pressure. Therefore, it is necessary to control the condensing pressure in a reasonable range, otherwise the refrigeration device will have frequent low-pressure alarm or low suction pressure alarm.

In order to avoid the winter operation risk of the cooling water system, we can start from ：the cooling tower equipment, cooling tower operation strategy and the end pipeline setting.

To avoid the winter operation risk through the equipment side anti freezing, cooling tower start-up and shutdown and pipeline optimization design.

1.There are TWO parts of antifreeze in the place of perennial operation or partial operation:

Spray Water System and Internal Circulating Water System (softened water)。

For the anti freezing problem of spray water system, an electric heater is usually added in the water pan, which is generally started when the spray water is lower than 5 ℃ and stops when the spray water is above 8 ℃.

The temperature probe transmits the signal to the control cabinet to automatically control the start and stop of the electric heater. The power selection of electric heater depends on circulating water volume and external air temperature.

2.Ethylene glycol solution or electric heating equipment can be added to prevent freezing of internal circulating water system.

The freezing point temperature of glycol solution should be selected below the local historical minimum temperature.

For the larger cooling system, we can consider digging a pool to put the spray water into it, which can save the power consumption due to electric heating operation.

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電子膨張弁と熱膨張弁の比較

電子膨張弁と熱膨張弁の比較

現在、ますます多くの民生用および商業用冷凍装置が、純正の熱式膨張弁の代わりに電子膨張弁を使用しています。電子膨張弁と熱式膨張弁は基本的な用途は同じですが、性能が異なります。

1. 調整範囲

At present, the regulating range of thermal expansion valve is generally narrow. The heat pump unit should not only refrigeration, but also heating, and the ambient temperature range of the suitable occasions is from – 15 ℃ ～ + 43 ℃、対応する冷媒蒸発温度は次の範囲で動作します。 – 25℃ – 5 ℃. In addition, if there are multiple compressors in the refrigeration circuit, the number of compressors in operation will change accordingly with the change of user load, resulting in dramatic change of refrigerant flow.

したがって、単一の熱式膨張弁では、大型のヒートポンプ ユニットの動作には適していません。現在、大規模ヒートポンプ製品の多くはシングルループ、シングルコンプレッサーで設計されており、独立した冷凍モードと暖房モードを備えた膨張弁システムが採用されており、システムの複雑さと製造コストが増加します。電子膨張弁は15％～100％の範囲で正確に調整可能です。

現在の使用効果によると、上記の条件下では単一の電子膨張弁でヒートポンプユニットの規制を満たすことができます。製品の特性に合わせて調整範囲を設定できるため、柔軟性が高まります。

2.過熱度の制御

(1) 過熱度制御点:

温度式膨張弁の場合、一般に蒸発器出口の過熱度のみを制御できます。セミクローズドおよびフルクローズドコンプレッサーシステムでは、制御点を蒸発器出口だけでなくコンプレッサー吸入ポートにも設定でき、コンプレッサーの吸入過熱度を制御してコンプレッサーの効率を確保できます。

(2)過熱度設定値：

温度式膨張弁の場合、過熱度設定値はメーカーが製造工程で設定するのが一般的で、通常は5℃、6℃、または8℃です。電子膨張弁の過熱度は、製品のさまざまな特性に応じて手動で設定できます。たとえば、蒸発器出口の過熱度を 6 ℃、コンプレッサー吸入の過熱度を 15 ℃ に設定することができ、非常に柔軟です。

(3) 標準以外の運転条件下での過熱度制御の安定性:

温度式膨張弁の過熱設定値は全て標準状態での設定値です。しかし、充填する作動流体の特性上、システムが標準使用条件から逸脱すると、凝縮圧力の変化に伴い過熱度が設定値から外れ、システム効率の低下を引き起こすだけでなく、システムの変動を引き起こすことになります。電子膨張弁の過熱度はコントローラーによって人為的に設定され、システムの実際の過熱度はセンサーが収集した制御点のパラメータから計算されるため、このような問題はありません。

(4) システム規制のインテリジェンス:

温度式膨張弁の過熱度制御は、充填された作動流体の特性によって決まる電流制御点の状態に基づいて行われます。システムの変化傾向を判断することはできません。電子膨張弁の制御ロジックは、さまざまな製品の設計および製造特性に応じて、さまざまなインテリジェント制御システムを採用できます。システムの現在の状態を調整するだけでなく、過熱度の変化率やその他のパラメーターに応じてシステムの特性を区別することもできます。さまざまなシステム変化の傾向に応じて、対応する制御方法が採用されます。そのため、温度式膨張弁よりも応答速度やシステム変化への追従性が優れています。

3. 反応速度

The thermal expansion valve is driven by taking advantage of the thermal characteristics of the filling working medium, so its opening and closing characteristics are as follows:

(1) The sensitivity of reaction and the speed of opening and closing are slow.

(2) Generally speaking, the opening and closing speed of thermal expansion valve is relatively consistent.

(3) In the process of unit start-up, there is static superheat. The superheat (SH) of thermal expansion valve is composed of static superheat (SS) and opening superheat (OS). Due to the existence of static superheat, there will be a tendency to delay the opening of thermal expansion valve during startup.

電子膨張弁の駆動モードは、コントローラーがセンサーによって収集されたパラメータを計算し、調整コマンドを駆動ボードに送信し、駆動ボードが電子膨張弁に電気信号を出力して電子膨張弁の動作を駆動します。電子膨張弁は全閉から全開までわずか数秒で変化します。反応速度、動作速度が速く、静的な過熱現象がありません。また、開閉特性や開閉速度を手動で設定できるため、運転条件の変動が激しいヒートポンプユニットの使用に特に適しています。

4. 多彩な制御機能

ユニットの初期起動時に過剰な冷媒圧力と蒸発側流量によって引き起こされるコンプレッサーの過負荷を防ぐために、温度式膨張弁には一般にモップ機能が装備されています。つまり、蒸発圧力が設定値より低い場合にのみ膨張弁が開きます。しかし、電子膨張弁と比較すると、その機能はまだ単調です。

電子膨張弁の構造は、スロットル機構と電磁弁を有機的に組み合わせたものと考えられ、コントローラによって調整することができます。したがって、さまざまな製品特性に応じて、ユニットの起動、負荷変化、霜取り、シャットダウン、および故障保護の条件下で制御機能の多様性と優位性を示します。たとえば、冷媒の流れを調整する電子膨張弁は、蒸発器を制御するだけでなく、凝縮器の調整にも使用できます。

蒸発条件が許せば、凝縮圧力が高すぎる場合は、膨張弁を適切に閉じてシステム内の冷媒流量と凝縮器の負荷を軽減し、凝縮圧力を下げてユニットの効率的かつ信頼性の高い動作を実現することができます。

電子膨張弁と熱膨張弁の比較 Read More »

冷水チラーの動作シーケンス

冷水チラーの動作シーケンス

1.CHECK LIST BEFORE INPUT POWER

WHEN the power supply and water supply both meet the requirements,then can we input the power:FIRST, press the power button ON, and check :

① LIQUID LEVEL AND OPEN THE PUMP VALVE:

Whether the liquid level of the cold water tank meets the requirements and whether the front and rear valves of the cold water pump have been opened;

② OPEN THE WATER TOWER AND PUMP

Turn on the switch of cooling water tower and cooling water pump, and pay attention to the opening of inlet and outlet valves of cooling water. (Note: air cooled type does not need cooling water tower)

③CHECK THE TURNING DIRECTION

When all the above conditions are met, you can use the inching mode to test whether the direction of cooling water pump, cold water pump, cooling tower fan and condensing fan of air cooling unit is correct, and whether the water transmission and air suction and discharge are normal. If not, they must be eliminated first.

2. PRESS THE CHILLER OPEN BUTTON AND LET IT RUN

Turn on the running switch of the chiller again, and the chilled water pump starts to run. Please note that the inlet and outlet valves of the chilled water must be opened, and the compressor will run automatically after the delay switch. Please check and adjust the required temperature.

3. Startup sequence difference of water-cooled and air-cooled chiller:

① Water cooled chiller unit:

turn on the cooling tower fan and cooling water pump first, and then turn on the chiller

② Air cooled chiller unit:

can be started directly

4. Shutdown sequence:

① Water cooled unit:

turn off the chiller first, then turn off the cooling tower fan and cooling water pump

② Air cooled unit:

It can be shut down directly.

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工業用冷水器の設置

工業用冷水チラーの設置要件

Installation Requirements of Industrial Water Chiller

All the Installation requirements of industrial water chiller you should notice to make sure the chilling unit can run as long as it can.

Industrial chillers can be divided into two categories according to the heat dissipation mode: 1. Water cooling units; 2. Air cooling units.

The water-cooled unit must be connected with the cooling tower and the inlet and outlet pipes of cooling water and chilled water. The cooling tower and cooling pump should be selected according to the refrigeration capacity and compression power, with the inlet pressure ≥ 1.5bar, and the diameter of the inlet and outlet pipe should be consistent with the diameter of the cooling water inlet and outlet pipe.

However, the air-cooled unit only needs to connect the chilled water inlet and outlet pipes and make-up water source. After the power supply is connected, the operation can be carried out. The ventilation should be smooth, and there should be no dust and debris around to avoid being inhaled into the unit.

1。The diameter of the water pipe

The diameter of the water pipe connection port reserved by the unit is standard size. When the remote transmission is adopted, a larger diameter water pipe must be used for connection. In any case, the diameter of the water pipe should not be smaller than the standard diameter of the connection port, otherwise, the pressure alarm will be given and the compressor and water pump will be damaged greatly.

2。Connecting The Water Pipe

When connecting the water pipe, the user should refer to the installation diagram to connect the pipeline, confirm the position of the inlet and outlet pipe, distinguish the cooling water pipe and the chilled water pipe.The wrong connection of the pipe will damage the unit.Only after ensuring the normal connection of the whole system can the system be started up and run.

3。With Connector or Flange

When the water pipe is connected to the unit, it must be connected with a connector or flange, so that it can be easily removed when necessary.

4.Connect a Hose

A section of hose is connected to the outlet and inlet of the water pipe to reduce vibration transmission.

5.Valves and Filter

If permitted, install valves on water pipes to effectively control water flow. It is suggested to install a filter at the water inlet to prevent sediment and debris.

6。Check Leakage Problem

Check the internal and external have leakage problem or not,when the water inlet/outlet valve of evaporator and condenser is fully opened.

7。Wrap With Insulation Material

The water pipe should be wrapped with enough insulation cotton to protect it from frost on the surface and keep the chilling water temperature.

8.Winter Protection Measures

In winter, when the unit stops operation, the water in the water pump and water pipe may freeze, causing damage to the unit and water pipe. In order to prevent icing, when the unit stops, the water pump can be effectively started. If there is still possibility of icing, all water in the water pipe will be discharged. If drainage is difficult, an anti icing mixture such as ethylene glycol or propanol can be used.

9.By-pass Pipe

When installing the unit, please install the bypass pipe in the chilled water pipeline device. When the chilled water outlet valve is turned down, the bypass pipe valve can be adjusted to relieve the pump pressure and prevent the evaporator from freezing.

10.Check Before Running

When the air-cooled chiller is started up and running, please pay attention to whether the water pump and exhaust fan turn normally before starting up and running.

11.High/Low Pressure

When the unit is running, please pay attention to the pressure display content: water cooled high pressure is (1.2 ~ 1.8MPa), low pressure is (0.3 ~ 0.6MPa); air cooled high pressure is (1.2 ~ 1.9mpa), low pressure is (0.3 ~ 0.6MPa). If the value is too high or too low, it means that the fault is a precursor or improper use. Please check it in time or inform the manufacturer to deal with it. Maintenance in advance is better than repair afterwards.

12.Cooling Water and Scale

To ensure that the condenser is not easy to scale and can be used for a long time, please use softened water (or tap water) as cooling water. If a cooling tower is used, the cooling water should be replaced regularly.

13.Regular Cleanning

The condenser and evaporator of the chiller usually need to be cleaned after a period of use (the cleaning cycle depends on the surrounding environment and water quality).

14.Temperature Setting

It is better to control the outlet water temperature of the unit at 7 ~ 12 ℃. When adjusting the temperature controller, please note that low temperature will cause some protection devices of the unit to fail.

15.Electric Control Elements and Protection Devices

All electric control elements and protection devices of the unit have been strictly tested by the manufacturer. Users are not allowed to change or remove them during inspection and maintenance. Forced operation without protection will cause great damage to the unit.

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さまざまなタイプのチラーの特徴と利点

Characteristics and advantages of
different types Water Chillers

1。

Box type water cooling chiller:

It has compact structure, with water tank and water pump inside. It is suitable for equipment with closed external pipeline.

The water-cooled model needs to be equipped with cooling water pump and cooling tower before it can be put into use.

2。

Box type air-cooled chiller:

In addition to all the performance of box type, there is no need to add cooling water pump and cooling tower.

It is easy to install and operate. It is suitable for small flexible production equipment and workshop where cooling tower is installed unconditionally.

3。

Water cooled open type water chiller:

It is not equipped with chilled water tank and water pump, but can be connected with water pump and water tank as required.

The volume of water tank and pump head are not limited, which can better meet the needs of different industrial equipment.

Open structure, easy to clean and maintain.

4.

Water cooled or air-cooled low-temperature chillers:

Antifreeze solution (ethylene glycol or low-temperature brine) should be used as the carrier refrigerant, and the outlet temperature can be below zero.

It includes three series: high temperature (water outlet temperature: 3 ℃ – 5℃）、中温（出水温度： – 5℃ – 10℃）、低温（出水温度） – 15 ℃), which can meet the low temperature requirements of various equipment and can also be customized according to the special requirements of customers.

5.

Water cooled screw type:

Adopted with shell and tube condenser and shell and tube condenser , which have the characteristics of simple structure, stable heat exchange, long-lasting efficiency and convenient maintenance.

The unit has reliable safety protection devices, including: high and low voltage protector, exhaust overheat protector, compressor motor overheat protector, overload current protector, antifreeze temperature protector, water flow protector, emergency stop switch, temperature sensitive fusible bolt, safety valve, etc.

It is recognized as the most ideal structure composition of central refrigeration host.

6。

Corrosion resistant titanium tube type:

Special titanium evaporator can avoid acid liquid corrosion, and can directly freeze electroplating, oxidation liquid, sea water, salt water and other corrosive liquids.

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冷水器設置前の準備

Find it hard or complicate to install a water chiller? Don’t know how to pick up a right place to settle your new water chiller?

Actually , you just need to do below steps one by one.Then everything will become very simple.

Let’s do it！

Check the components are complete

Before installation, check whether the components of the unit are complete.

The Right Cooling water tower and Cooling water pump

Select the appropriate cooling tower (air cooling type does not need cooling tower), and the capacity of cooling water pump should match the model. Please install according to the size of the body pipe, do not reduce the size of the cooling pipe, in order to avoid causing high pressure overload, affecting the cooling effect and increasing power consumption.

Correct handling methods

Correct handling method: use stacker, crane and drum. Do not drag the machine by force. Since the equipment has been debugged before leaving the factory, the system has pressure, so strong vibration is not allowed during loading and unloading, handling and installation. It is not allowed to invert, tilt or side set the unit during handling.

The right installation location requested:

The water chiller is an indoor device. If the user needs to place the equipment outdoors, it should be well protected from rain and sun, and should not be directly exposed to the outside.

 

The installation location should be a place with stable foundation, open surroundings, ventilation, avoiding corrosion and pollution, and convenient for installation and maintenance.

Since the unit itself will generate heat, it is necessary to avoid high temperature area around the unit during installation to meet the effective heat dissipation of the equipment, especially to ensure that the condenser of air-cooled chiller is well ventilated.

Avoid placing high-power inverter, welding machine and other equipment with interference sources near the equipment, and the installation space of the unit shall not be less than the size shown in the figure below. The figure shows the minimum installation space of the unit (unit: mm).

Water-cooled water chiller (Box type or Open type)
Air-cooled water chiller

The unit without caster at the bottom

The unit without caster at the bottom must be placed on the horizontal concrete base, and there must be no less than 3mm thick damping rubber pad between the unit and the concrete base

It is better to install large air-cooled units in outdoor space。

On the other hand, it can reduce heat emission. When placing, please support the bottom of the unit with bracket to make it ventilate smoothly and prevent rusting.

Note:

(1) the power load and grounding part shall be constructed in accordance with relevant laws and regulations

(2) The chilled water pipes of newly installed chillers must be covered with insulation layer.

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APT業界のチラーの適用

2021年の冷凍技術の応用

冷凍産業の発展に伴い、冷凍技術の応用はますます広範囲になってきています。今では、日常の衣・食・住・交通から最先端の科学技術に至るまで、人々の生活・生産活動のあらゆる分野に浸透しており、冷凍技術は欠かすことができません。

1. 食品工学

 

生鮮食品の品質、経済寿命、価値を長く向上させるためには、生鮮食品の仕入れや漁獲から、加工、保管、輸送、販売に至るまでの流通過程全体において、安定した低温環境を維持する必要があります。そのためには、冷蔵加工設備、冷蔵倉庫、冷蔵輸送車両や船舶、冷蔵販売カウンターなど、さまざまな冷蔵設備が必要となります。

 

2. 空調工学

空調工学は冷凍技術の幅広い応用分野です。光学機器、精密測定ツール、繊維工場、コンピューター室などでは、環境の温度、湿度、清浄度をさまざまなレベルで管理する必要があります。体育館や大ホール、ホテルなどの公共施設、自動車、飛行機、大型バスにも快適な空調システムが求められています。

3. Mechanical and electronic industry

20HP産業用水冷チラー

 

精密工作機械の油圧システムは冷凍を利用して油温を制御し、油膜の硬さを安定させて機械を正常に動作させることができます。鋼の低温処理により、鋼の特性が改善され、鋼の硬度と強度が向上し、ワークピースの耐用年数が延長されます。マルチチャンネル通信、レーダー、衛星地上局、その他の電子機器も低温で動作する必要があります。

 

スイミングプール水チラー 1HP-3HP

血漿、ワクチン、および一部の特殊な薬剤は低温で保存する必要があります。低温麻酔、低温手術、高熱患者の冷湿布冷却にも冷凍技術が必要です。

4. National defense industry and modern science

It is also necessary to simulate the performance

of these weapons and vehicles in the cold environment. Artificial rainfall also needs cooling.

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