JP2009276004A - Free cooling effectiveness-determining method for free cooling system - Google Patents

Free cooling effectiveness-determining method for free cooling system Download PDF

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JP2009276004A
JP2009276004A JP2008128327A JP2008128327A JP2009276004A JP 2009276004 A JP2009276004 A JP 2009276004A JP 2008128327 A JP2008128327 A JP 2008128327A JP 2008128327 A JP2008128327 A JP 2008128327A JP 2009276004 A JP2009276004 A JP 2009276004A
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cooling
free
water
free cooling
heat exchanger
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Yuzuru Higo
譲 肥後
Susumu Ikeda
進 池田
Kosuke Ando
幸助 安藤
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Hitachi Building Systems Co Ltd
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Hitachi Building Systems Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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    • Y02B30/54—Free-cooling systems

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Abstract

<P>PROBLEM TO BE SOLVED: To use free cooling with respect to each time zone even in an intermediate season and exhibit high energy saving effects. <P>SOLUTION: This free cooling system is provided with two or more refrigerating facility units 1, 2 having cooling towers 11, 21 and refrigerating machines 12, 22 and with a free cooling heat exchanger 3 provided in any one of the refrigerating facility units 1, 2 and performing heat exchange between cooling water in the cooling tower and cooled side cold water. Based on free cooling capacity Q obtained from inlet temperature Tci of cooling water to the cooling tower 11 or cold water inlet temperature Tei-Δt of the heat exchanger 3 and atmosphere wet-bulb temperature Twb, it is determined whether or not heat exchange between the cooling tower cooling water and the cooled side cold water by the free cooling heat exchanger 3 is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明はクーリングシステムに係り、特に半導体製造工場等の冬期に冷房負荷がある工場等で用いられるフリークーリングシステムのフリークーリング有効・無効判定方法に関する。   The present invention relates to a cooling system, and more particularly to a free cooling validity / invalidity determination method of a free cooling system used in a factory having a cooling load in winter such as a semiconductor manufacturing factory.

半導体工場、電算機センター、大型店舗においては、冬期においても冷房負荷、冷却負荷がある。近年では、既設の冷却塔や、専用の冷却塔を追設し外気を利用し省エネルギー効果の大きいフリークーリングシステムが導入されている。フリークーリング有効/無効の判定は冷却塔の冷却水出口温度が設定温度に比べて高いか低いかによって決めていた（特許文献１、特許文献２参照）。
特開２００４−１３２６５１公報 特開２００４−３４０４９２公報 Semiconductor factories, computer centers, and large stores have cooling and cooling loads even in winter. In recent years, an existing cooling tower or a dedicated cooling tower has been additionally installed and a free cooling system having a large energy saving effect using outside air has been introduced. Whether the free cooling is valid / invalid is determined by whether the cooling water outlet temperature of the cooling tower is higher or lower than the set temperature (see Patent Document 1 and Patent Document 2).
JP 2004-132651 A JP 2004-340492 A

冷却水の入口温度（フリークーリング熱交換器への入口温度）が設定温度程度以上であったとしても，フリークーリング熱交換器において前記冷却水と熱交換する被冷却側冷水の温度が冷却水の温度を上回っていれば，冷却水で被冷却側冷水を冷却することができる状況にある。しかし，前述した従来の技術では、フリークーリングによる冷却能力が有効に存在するにも拘わらずフリークーリングは無効となってしまい，省エネルギー、省コストの機会を失うことになる。また，負荷が時間帯によって変動するものにあっては，時間帯単位のフリークーリングモードでの運転も的確に行えない問題がある。   Even if the inlet temperature of the cooling water (the inlet temperature to the free cooling heat exchanger) is about the set temperature or higher, the temperature of the cooled cold water that exchanges heat with the cooling water in the free cooling heat exchanger is If it is above the temperature, the cooled water can be cooled with the cooling water. However, in the conventional technology described above, the free cooling becomes invalid despite the effective cooling capacity by free cooling, and the opportunity for energy saving and cost saving is lost. In addition, when the load fluctuates depending on the time zone, there is a problem that the operation in the free cooling mode for each time zone cannot be performed accurately.

本発明の目的は，フリークーリング能力が存在する限り最大限に利用可能とするフリークーリングシステムのフリークーリング有効・無効判定方法を提供することにある。   An object of the present invention is to provide a free cooling effective / invalid determination method of a free cooling system that can be used to the maximum as long as free cooling capability exists.

本発明の他の目的は、負荷が時間帯によって変動する場合であっても，時間帯単位のフリークーリングモードでの運転を的確に行うことができるフリークーリングシステムのフリークーリング有効・無効判定方法を提供することにある。   Another object of the present invention is to provide a free cooling effective / invalid determination method for a free cooling system capable of accurately performing operation in a free cooling mode in units of time zones even when the load varies with time zones. It is to provide.

上記目的を達成するため本発明の１番目は，冷却塔，冷凍機を有する２基以上の冷凍設備ユニットと，任意の一基に設けられ，冷却塔の冷却水と被冷却側冷水と熱交換するフリークーリング熱交換器とを備えたフリークーリングシステムのフリークーリング有効・無効判定方法において，前記冷却塔のフリークーリング能力に基づいて，フリークーリング熱交換器による冷却塔冷却水と被冷却側冷水との熱交換を行うか否かを判定することを特徴とし，２番目の発明は，冷却塔，冷凍機を有する２基以上の冷凍設備ユニットと，任意の一基に設けられ，冷却塔の冷却水と被冷却側冷水と熱交換するフリークーリング熱交換器とを備えたフリークーリングシステムのフリークーリング有効・無効判定方法において，前記冷却塔の冷却水入口温度と外気湿球温度から求められるフリークーリング能力に基づいて，フリークーリング熱交換器による冷却塔冷却水と被冷却側冷水との熱交換を行うか否かを判定することを特徴とし，３番目の発明は，請求項１において，冷却塔のフリークーリング能力は，冷却塔冷却水入口温度の代わりにフリークーリング熱交換器の被冷却側冷水入口温度から求めた値を用いることを特徴とするものである。   In order to achieve the above object, the first aspect of the present invention is a heat exchange between the cooling water of the cooling tower and the cooled water on the cooled side, provided in one or more refrigeration equipment units having a cooling tower and a refrigerator. In the free cooling effective / invalid determination method of the free cooling system including the free cooling heat exchanger, the cooling tower cooling water and the cooled side cooling water by the free cooling heat exchanger are determined based on the free cooling capacity of the cooling tower. The second invention is provided in any one of two or more refrigeration equipment units having a cooling tower and a refrigerator, and is used for cooling the cooling tower. In a free cooling effective / invalid determination method of a free cooling system having a free cooling heat exchanger for exchanging heat with water and cold water to be cooled, the cooling water inlet temperature of the cooling tower is determined. The third invention is characterized in that whether or not heat exchange between cooling tower cooling water and cooled side cooling water by a free cooling heat exchanger is performed based on the free cooling capacity obtained from the outside wet bulb temperature. In claim 1, the free cooling capacity of the cooling tower is characterized in that a value obtained from the cooled side cold water inlet temperature of the free cooling heat exchanger is used instead of the cooling tower cooling water inlet temperature. .

本発明は上記のように，フリークーリングの有効・無効の判定（フリークーリング熱交換器での冷却塔冷却水と被冷却側冷水との熱交換を行うか否かの選択）を，フリークーリング熱交換器に対する冷却水の入口温度または被冷却側冷水の入口温度と大気の湿球温度とに基づいて求められる冷却塔のフリークーリング能力で行っているため，冷却水が被冷却側冷水温度より低い温度になれば，冷却水による被冷却側冷水の冷却が可能となり，かつ，このときにおける冷却水の入口温度または被冷却側冷水の入口温度と大気の湿球温度とに基づいて求められる冷却塔のフリークーリング能力が０（零）を上回っていれば，フリークーリングが有効となる。要するに，冷却水の入口温度が被冷却側冷水の入口温度より低いかまたは所定温度以上低く，かつ冷却塔のフリークーリング能力が０（零）を上回っている場合に冷却水による被冷却側冷水の冷却が行われるので，フリークーリング能力が存在する限り，これを最大限に利用可能とする効果がある。これにより，負荷の変化だけでなく，１日の中での湿球温度の変化に対応してフリークーリングの有効・無効の判定が行なわれ，冷却水の入口温度に影響を与える大気温度が，被冷却側冷水温度に次第に近づいてくる中間季においても時間帯ごとにフリークーリングを利用可能とし，高い省エネルギー効果を発揮する効果がある。   As described above, the present invention determines whether free cooling is valid or invalid (selection of whether or not to perform heat exchange between cooling tower cooling water and cooled cold water in the free cooling heat exchanger). The cooling water is lower than the cooled-side cold water temperature because the cooling tower free cooling capacity is calculated based on the inlet temperature of the cooling water to the exchanger or the inlet temperature of the cooled cold water and the wet bulb temperature of the atmosphere. When the temperature reaches, the cooling-side cold water can be cooled by the cooling water, and the cooling tower can be obtained based on the inlet temperature of the cooling water or the inlet temperature of the cooling-side cold water and the atmospheric wet bulb temperature at this time. If the free-cooling capacity of exceeds 0 (zero), free-cooling is effective. In short, when the cooling water inlet temperature is lower than the inlet temperature of the cooled side cold water or lower than the predetermined temperature and the free cooling capacity of the cooling tower exceeds 0 (zero), Since cooling is performed, as long as free cooling capability exists, this has the effect of making the maximum use possible. This makes it possible to determine whether free cooling is effective or invalid in response to changes in wet bulb temperature throughout the day as well as changes in load, and the atmospheric temperature that affects the inlet temperature of the cooling water Even in the mid-season that gradually approaches the temperature of the chilled water on the cooled side, free cooling can be used in each time zone, and there is an effect of exhibiting a high energy saving effect.

以下、本発明を適用したフリークーリングシステムの制御装置の一例を図により説明する。   Hereinafter, an example of a control device of a free cooling system to which the present invention is applied will be described with reference to the drawings.

図１はフリークーリングシステムの系統図であり，一実施形態に係わるフリークーリングシステムは，第１冷却設備ユニット１，第２冷却設備ユニット２，第１冷却設備ユニット１だけに接続されているフリークーリング用の熱交換器３，供給側冷水ヘッダー４，戻り側冷水ヘッダー５，フリークーリング制御装置（以下単に制御装置と言う）６を備えている。図において，符号５０は，被冷却空間に配置される１または複数の空調ユニットを示している。第１，第２の冷却設備ユニット１，２は，ほぼ同じ構成となっており，冷却水と大気との直接熱交換によってより低い温度の冷却水を生成する冷却塔１１（２１），吸収式冷凍機１２（２２）で構成され，吸収式冷凍機１２（２２）の構成は，一般に知られているので詳細な説明は省略するが，主要機器としは加熱源付きの再生器，凝縮器，蒸発器および吸収器を備えている。吸収式冷凍機の代わりに圧縮式冷凍機を利用することもでき，圧縮式冷凍機の場合は，圧縮機，凝縮器，膨張手段，蒸発器を備えている。冷却塔１１（２１）は，冷凍機１２（２２）の吸収器，凝縮器（圧縮式冷凍機の場合は凝縮器）と冷却水往き配管１３（２３），冷却水戻り配管１４（２４）を介して接続されている。供給側冷水ヘッダー４は，冷凍機１２（２２）の蒸発器（図示せず）の被冷却側冷水の出口側（本願では冷水出口側という）と往き冷水配管７（８）を介して接続され、戻り側冷水ヘッダー５は，冷凍機１２（２２）の蒸発器（図示せず）の被冷却側冷水の入口側（本願では冷水入口側という）と戻り冷水配管９（１０）を介して接続されている。前記冷却水往き配管１３（２３）の途中にはポンプ１５（２５）が設置され，戻り冷水配管９（１０）の途中にはポンプ１６（２６）が設置されている。   FIG. 1 is a system diagram of a free cooling system. A free cooling system according to an embodiment is a free cooling system connected only to a first cooling equipment unit 1, a second cooling equipment unit 2, and a first cooling equipment unit 1. A heat exchanger 3, a supply side cold water header 4, a return side cold water header 5, and a free cooling control device (hereinafter simply referred to as a control device) 6. In the figure, reference numeral 50 indicates one or a plurality of air conditioning units arranged in the space to be cooled. The first and second cooling equipment units 1 and 2 have substantially the same configuration, and a cooling tower 11 (21) that generates lower temperature cooling water by direct heat exchange between the cooling water and the atmosphere, an absorption type The structure of the refrigerating machine 12 (22) and the structure of the absorption refrigerating machine 12 (22) are generally known and will not be described in detail, but the main equipment is a regenerator with a heating source, a condenser, Evaporator and absorber are provided. A compression refrigerator can be used instead of the absorption refrigerator, and the compression refrigerator includes a compressor, a condenser, expansion means, and an evaporator. The cooling tower 11 (21) includes an absorber, a condenser (condenser in the case of a compression type refrigerator), a cooling water return pipe 13 (23), and a cooling water return pipe 14 (24) of the refrigerator 12 (22). Connected through. The supply side cold water header 4 is connected to the outlet side of the cooled side cold water (referred to herein as the cold water outlet side) of the evaporator (not shown) of the refrigerator 12 (22) via the outgoing cold water pipe 7 (8). The return side cold water header 5 is connected to the cooled side cold water inlet side (referred to as the cold water inlet side in this application) of the evaporator (not shown) of the refrigerator 12 (22) via the return cold water pipe 9 (10). Has been. A pump 15 (25) is installed in the middle of the cooling water piping 13 (23), and a pump 16 (26) is installed in the middle of the return cold water piping 9 (10).

フリークーリング用熱交換器３は，冷却水と被冷却側冷水（本願では冷水という）との間で熱交換するものであって，冷却水側配管３１，冷水側配管３２を有し、冷却水側配管３１は，その入口側が往き冷却水配管１３の途中（ポンプ１５の出口側）に接続され，出口側が冷却水戻り配管１４の途中にそれぞれ接続されている。冷水側配管３２は，その入口側が戻り冷水配管９の途中（ポンプ１６の出口側）に接続され，出口側が往き冷水配管７の途中にそれぞれ接続されている。冷却水側配管３１の入口側および出口側には弁３３，３４が設置され，冷水側配管３２の出口側には弁３５が設置されている。前記往き冷却水配管１３上の冷却水側配管３１出口接続箇所と吸収式冷凍機１２の吸収器（圧縮式冷凍機場合は凝縮器）との間の箇所に弁１７が介在され、冷却水戻り配管１４上の冷却水側配管３１入口接続箇所と吸収式冷凍機１２の凝縮器（圧縮式冷凍機場合は凝縮器）との間の箇所に弁１８が介在され、戻り冷水配管９上の冷水側配管３２の入口接続箇所と吸収式冷凍機１２の蒸発器（圧縮式冷凍機場合は蒸発器）との間の箇所に弁１９が介在されている。空調ユニット５０は，供給側冷水ヘッダー４と二次往き冷水配管２７を介して接続され，戻り側冷水ヘッダー５と二次戻り冷水配管２８を介して接続されている。供給側冷水ヘッダー４と戻り側冷水ヘッダー５とは，途中に弁２９を介在した配管で互いに連絡されている。前記弁１７，３４の代わりに三方切替弁（冷却水往き配管１３と冷却水側配管３１との接続部に配置）を用い，前記弁１８，３３の代わりに三方切替弁（冷却水戻り配管１４と冷却水側配管３１との接続部に配置）を用いることもできる。図において，符号４０，４１，４２は，温度センサーであり，温度センサー４０は，大気の湿球温度を計測し，温度センサー４１は，冷却水戻り配管１４の温度を計測し，温度センサー４２は，戻り冷水配管９内を通る戻り冷水の温度（入口温度）を計測するものである。制御装置６は，第１冷却設備ユニットフリークーリング運転回路６１，第１冷却設備ユニット冷凍機運転回路６２，第２冷却設備ユニット冷凍機運転回路６３，前記の温度センサー４０，４１，４２から取込んだ各計測データに基づいて冷却塔１１のフリークーリング能力Ｑ，前記の弁１７，１８，１９，３３，３４，３５の開閉を制御する機能，前記の第１，第２冷却設備ユニットの冷凍機１２，２２の起動・停止，冷却能力調整の機能等を備えている。   The free-cooling heat exchanger 3 exchanges heat between cooling water and cooled side cold water (referred to as cold water in the present application), and includes a cooling water side pipe 31 and a cold water side pipe 32. The side pipe 31 has an inlet side connected to the middle of the outgoing cooling water pipe 13 (the outlet side of the pump 15) and an outlet side connected to the middle of the cooling water return pipe 14. The inlet side of the cold water side pipe 32 is connected to the middle of the return cold water pipe 9 (the outlet side of the pump 16), and the outlet side is connected to the middle of the outgoing cold water pipe 7. Valves 33 and 34 are installed on the inlet side and the outlet side of the cooling water side pipe 31, and a valve 35 is installed on the outlet side of the cold water side pipe 32. A valve 17 is interposed between the outlet of the cooling water side pipe 31 on the outgoing cooling water pipe 13 and the absorber of the absorption refrigerator 12 (condenser in the case of a compression refrigerator) to return the cooling water. A valve 18 is interposed at a location between the cooling water side piping 31 inlet connection location on the piping 14 and the condenser of the absorption refrigeration machine 12 (condenser in the case of a compression refrigeration machine), and chilled water on the return chilled water piping 9. A valve 19 is interposed at a location between the inlet connection location of the side pipe 32 and the evaporator of the absorption refrigeration machine 12 (evaporator in the case of a compression refrigeration machine). The air conditioning unit 50 is connected to the supply-side chilled water header 4 via the secondary outgoing chilled water pipe 27, and is connected to the return-side chilled water header 5 via the secondary return chilled water pipe 28. The supply-side cold water header 4 and the return-side cold water header 5 are connected to each other through a pipe having a valve 29 interposed therebetween. Instead of the valves 17 and 34, a three-way switching valve (arranged at the connection between the cooling water outlet pipe 13 and the cooling water side pipe 31) is used, and instead of the valves 18 and 33, a three-way switching valve (cooling water return pipe 14 is provided). And a connection portion between the cooling water side pipe 31 and the cooling water side pipe 31 can also be used. In the figure, reference numerals 40, 41, and 42 denote temperature sensors, the temperature sensor 40 measures the wet bulb temperature in the atmosphere, the temperature sensor 41 measures the temperature of the cooling water return pipe 14, and the temperature sensor 42 The temperature (inlet temperature) of the return chilled water passing through the return chilled water pipe 9 is measured. The control device 6 takes in from the first cooling equipment unit free cooling operation circuit 61, the first cooling equipment unit refrigerator operating circuit 62, the second cooling equipment unit refrigerator operating circuit 63, and the temperature sensors 40, 41, 42. The free cooling capacity Q of the cooling tower 11, the function of controlling the opening and closing of the valves 17, 18, 19, 33, 34, and 35 based on each measurement data, the refrigerators of the first and second cooling equipment units. 12 and 22 are provided with functions for starting / stopping and adjusting the cooling capacity.

冷却塔１１のフリークーリング能力Ｑは，冷却水の冷却塔１１の入口温度（温度センサー４１による計測値）と大気の湿球温度（温度センサー４０による計測値）に基づいて演算する。また，前記冷却水の冷却塔１１の入口温度の代わりに戻り冷水配管９内を通る戻り冷水の温度（温度センサー４２による計測値）から所定値（たとえば３℃）程度を減算した値に基づいて演算する。   The free cooling capacity Q of the cooling tower 11 is calculated based on the inlet temperature of the cooling water cooling tower 11 (measured value by the temperature sensor 41) and the wet bulb temperature of the atmosphere (measured value by the temperature sensor 40). Further, based on a value obtained by subtracting a predetermined value (for example, 3 ° C.) from the temperature of the return chilled water passing through the return chilled water pipe 9 (measured by the temperature sensor 42) instead of the inlet temperature of the cooling tower 11 of the cooling water. Calculate.

フリークーリングは，冷却塔１１の冷却水は熱交換器３を介して、冷却水により冷水を冷却するために利用するものであり，冷却水の温度は，冷水より常に低い必要がある。つまり、冷却水で冷水を冷却するためには下記の(１)，(２)式が必要条件となる。   In the free cooling, the cooling water in the cooling tower 11 is used for cooling the cold water with the cooling water via the heat exchanger 3, and the temperature of the cooling water must always be lower than that of the cold water. That is, the following formulas (1) and (2) are necessary conditions for cooling the cold water with the cooling water.

Ｔwb＜Ｔci＜Ｔei ・・・・・・(１)
Ｑ＞０ ・・・・・・(２)
ここで Ｔwb：大気(外気)湿球温度
Ｔci：熱交換器３から冷却塔１１に流入する冷却水の入口温度
Ｔei：熱交換器３に入る冷水の冷水入口温度
Ｑ：冷却塔のフリークーリング能力（ＱはＴｗｂとＴｃｉによる関数）
Ｑ(%)＝0.2×{Tci-(-0.0001×Tci+0.0041)×Twb２-0.185×Twb-(0.76×Tci+0.2)}
Ｑは冷却塔の定格能力に対する能力比で特性図から求めた近似式
そこで，本実施形態では，第１冷却設備ユニット１は，上記（１）および(２)の条件を満足したときには，運転モードをフリークーリング運転モードとし，運転状態とし，上記（１）および(２)の一方または両方の条件を満足しないとき，運転モードを冷凍機運転モードとし，運転停止の状態とする。第２冷却設備ユニット２は，温度センサー４２で計測される冷水入口温度が予め設定された基準値（基準値範囲の上限値）を上回ったときは，運転状態とし，基準値（基準値範囲の下限値）を下回ったときは，運転停止状態とする。また，第１冷却設備ユニット１がフリークーリング運転モードで運転中に，温度センサー４２で計測される冷水入口温度が予め設定された基準値（基準値範囲の上限値）を上回ったときは，先に第２冷却設備ユニット２を運転し，第２冷却設備ユニット２の運転中に，冷水入口温度が予め設定された基準値（基準値範囲の上限値）を上回ったときは，第１冷却設備ユニット１を冷凍機運転モードで運転する。この状態で冷水入口温度が基準値（基準値範囲の下限値）を下回ったときは，第１冷却設備ユニット１，第２冷却設備ユニット２の順で運転を停止する。 Twb <Tci <Tei (1)
Q> 0 (2)
Where Twb: Air (outside air) wet bulb temperature
Tci: inlet temperature of cooling water flowing from the heat exchanger 3 into the cooling tower 11
Tei: Cold water inlet temperature of cold water entering the heat exchanger 3
Q: Free cooling capacity of cooling tower (Q is a function of Twb and Tci)
Q (%) = 0.2 × {Tci − (− 0.0001 × Tci + 0.0041) × Twb 2 −0.185 × Twb− (0.76 × Tci + 0.2)}
Q is an approximate expression obtained from a characteristic diagram by a capacity ratio with respect to the rated capacity of the cooling tower. Therefore, in the present embodiment, the first cooling equipment unit 1 operates in the operation mode when the conditions (1) and (2) are satisfied. Is set to the free cooling operation mode, and the operation state is set. When one or both of the conditions (1) and (2) are not satisfied, the operation mode is set to the refrigerator operation mode and the operation is stopped. When the chilled water inlet temperature measured by the temperature sensor 42 exceeds the preset reference value (the upper limit value of the reference value range), the second cooling equipment unit 2 enters the operating state and sets the reference value (the reference value range of the reference value range). If the value falls below the lower limit, the operation is stopped. When the first cooling equipment unit 1 is operating in the free cooling operation mode, when the chilled water inlet temperature measured by the temperature sensor 42 exceeds a preset reference value (the upper limit value of the reference value range), When the second cooling equipment unit 2 is operated and the chilled water inlet temperature exceeds the preset reference value (the upper limit value of the reference value range) during the operation of the second cooling equipment unit 2, the first cooling equipment unit 2 is operated. Unit 1 is operated in the refrigerator operation mode. In this state, when the chilled water inlet temperature falls below the reference value (the lower limit value of the reference value range), the operation is stopped in the order of the first cooling equipment unit 1 and the second cooling equipment unit 2.

次に，第１冷却設備ユニット１の運転モードの選択のための制御を含めた詳細な動作を説明する。   Next, a detailed operation including control for selecting an operation mode of the first cooling equipment unit 1 will be described.

温度センサー４０で計測される大気湿球温度Ｔwb，温度センサー４１で計測される冷却水入口温度Ｔci，温度センサー４２で計測されるＴｅｉに基づいて演算し，上記（１），(２)式の両方を満足するかどうかを判定し，上記（１）および(２)式の両条件を満足したときには，制御装置６の第１冷却設備ユニットフリークーリング運転回路６１により，弁１７，１８，１９を閉じ，弁３３，３４，３５を開く。これにより冷却塔１１で生成された冷却水は，冷却水往き配管１３，ポンプ１５，弁３４，冷却水側配管３１を通り，熱交換器３に入り，ここで冷水と熱交換した後，冷却水側配管３１，弁３３，戻り冷却水配管１４を通り冷却塔１１に戻る。一方，冷水は戻り側冷水ヘッダ５から戻り冷水配管９，ポンプ１６，弁３５，冷水側配管３２を通り，熱交換器３に入り，ここで，冷却水と熱交換して冷却され，その後冷水側配管３２，往き冷水配管７を通り，供給側冷水ヘッダー４に入り，ここから二次往き冷水配管２７を介して空調ユニット５０に送られ，被空調空間を空調（冷却）した後，二次戻り冷水配管２８を介して戻り側冷水ヘッダー５に戻される運転すなわち，フリークーリング運転モードによるフリークーリングが行われる。このフリークーリング運転モードによる運転中に，たとえば空調負荷の増大により温度センサー４２で計測される冷水入口温度が基準値（基準値範囲の上限値）を上回った場合には，第２冷却設備ユニット２が運転され，第１冷却設備ユニット１によるフリークーリング運転と第２冷却設備ユニット２による冷水冷却運転とが行なわれる。   Calculation is performed based on the atmospheric wet bulb temperature Twb measured by the temperature sensor 40, the coolant inlet temperature Tci measured by the temperature sensor 41, and Tei measured by the temperature sensor 42, and the above equations (1) and (2) It is determined whether or not both are satisfied, and when both of the above conditions (1) and (2) are satisfied, the valves 17, 18 and 19 are controlled by the first cooling equipment unit free cooling operation circuit 61 of the control device 6. Close and open valves 33, 34 and 35. Thus, the cooling water generated in the cooling tower 11 passes through the cooling water outlet pipe 13, the pump 15, the valve 34, and the cooling water side pipe 31 and enters the heat exchanger 3, where it is heat-exchanged with the cold water, and then cooled. It returns to the cooling tower 11 through the water side pipe 31, the valve 33 and the return cooling water pipe 14. On the other hand, the cold water passes from the return side cold water header 5 through the return cold water pipe 9, the pump 16, the valve 35, and the cold water side pipe 32 and enters the heat exchanger 3, where it is cooled by exchanging heat with the cooling water and then cooled. After passing through the side pipe 32 and the forward chilled water pipe 7 and entering the supply side chilled water header 4, it is sent to the air conditioning unit 50 from here through the secondary forward chilled water pipe 27, and the air-conditioned space is air-conditioned (cooled). The operation of returning to the return side cold water header 5 through the return cold water pipe 28, that is, free cooling in the free cooling operation mode is performed. During the operation in the free cooling operation mode, for example, when the chilled water inlet temperature measured by the temperature sensor 42 exceeds the reference value (the upper limit value of the reference value range) due to an increase in the air conditioning load, the second cooling equipment unit 2 And the free cooling operation by the first cooling equipment unit 1 and the cold water cooling operation by the second cooling equipment unit 2 are performed.

一方，温度センサー４０で計測される大気の湿球温度の上昇，温度センサー４１で計測される冷却水入口温度（大気温度の影響を受ける）の変化（上昇），温度センサー４２で計測される冷水入口温度（空調負荷の影響を受ける）の変化（降下）によって，条件(１)，(２)の少なくとも一方が満足しなくなると，第２冷却設備ユニット２の運転・停止の状態に関係なく，第１冷却設備ユニットフリークーリング運転回路６１により，弁１７，１８，１９を開き，弁３３，３４，３５を閉じるとともに冷却塔１１の運転も停止される。これによりフリークーリング運転モードは解消され，冷凍機運転モードとなる（運転モードは冷凍機運転モードとなるが運転は停止状態）。このとき，もし，温度センサー４２で計測される冷水入口温度が基準値（基準値範囲の上限値）を上回った場合には，第２冷却設備ユニット２が運転される。   On the other hand, a rise in the wet bulb temperature of the atmosphere measured by the temperature sensor 40, a change (rise) in the cooling water inlet temperature (affected by the atmospheric temperature) measured by the temperature sensor 41, and a cold water measured by the temperature sensor 42 If at least one of the conditions (1) and (2) is not satisfied due to the change (decrease) in the inlet temperature (affected by the air conditioning load), regardless of whether the second cooling equipment unit 2 is operating or stopped, The first cooling equipment unit free cooling operation circuit 61 opens the valves 17, 18, 19 and closes the valves 33, 34, 35, and also stops the operation of the cooling tower 11. As a result, the free cooling operation mode is canceled and the refrigerator operation mode is set (the operation mode is the refrigerator operation mode, but the operation is stopped). At this time, if the chilled water inlet temperature measured by the temperature sensor 42 exceeds the reference value (the upper limit value of the reference value range), the second cooling equipment unit 2 is operated.

次に，冷却塔のフリークーリング能力Ｑの演算に，冷水の入口温度Ｔeiを用いた実施形態について説明する。   Next, an embodiment in which the cold water inlet temperature Tei is used to calculate the free cooling capacity Q of the cooling tower will be described.

前述したように、冷却塔のフリークーリング能力は使用する冷却塔１１の仕様が決まると，大気湿球温度Ｔwbと熱交換器３から冷却塔１１に入る冷却水の入口温度Ｔciによって決まる。大気湿球温度Ｔwbは大気の乾球温度と相対湿度から近似式を使い容易に求められる。ところが、フリークーリング運転モードによる運転時の冷却塔１１への冷却水の入口温度Ｔciは，熱交換器３に冷水と冷却水を流し、冷却塔１１を運転することで定常状態とった後に求められるが、定常状態となるためには一般的に１０〜１５分を要する。冷却水側配管３１が長く保有水量が多い場合には３０分程度を要することもある。さらに、冷却塔１１が稼動している場合でも、冷凍機１２の凝縮器を冷却する用途に使用している場合には冷却水温度を冷凍機保護のために一定値以上に保持するような手段を用いており、（例えば、冷却塔の送風量や冷却水量の抑制）、そのときの熱交換器３から冷却塔１１に入る冷却水の入口温度Ｔciをフリークーリング能力Ｑを演算させるために用いるのは最適とは言えない。そこで，この実施形態においては，熱交換器３から冷却塔１１に流入する冷却水の入口温度Ｔciの代わりに，熱交換器３に流入する冷水の入口温度Ｔei−Δｔを用いるものである。   As described above, when the specification of the cooling tower 11 to be used is determined, the free cooling capacity of the cooling tower is determined by the atmospheric wet bulb temperature Twb and the inlet temperature Tci of the cooling water entering the cooling tower 11 from the heat exchanger 3. The atmospheric wet bulb temperature Twb can be easily obtained from the dry bulb temperature of the atmosphere and the relative humidity using an approximate expression. However, the inlet temperature Tci of the cooling water to the cooling tower 11 during the operation in the free cooling operation mode is obtained after the cooling tower 11 is operated by flowing the cooling water and the cooling water through the heat exchanger 3 to obtain a steady state. However, generally 10 to 15 minutes are required to reach a steady state. When the cooling water side pipe 31 is long and the amount of retained water is large, about 30 minutes may be required. Further, even when the cooling tower 11 is in operation, when the cooling tower 11 is used for cooling the condenser of the refrigerator 12, the cooling water temperature is maintained at a predetermined value or more for protecting the refrigerator. (For example, suppression of the amount of air sent from the cooling tower and the amount of cooling water), and the inlet temperature Tci of the cooling water entering the cooling tower 11 from the heat exchanger 3 at that time is used to calculate the free cooling capacity Q. Is not optimal. Therefore, in this embodiment, the inlet temperature Tei−Δt of the cold water flowing into the heat exchanger 3 is used instead of the inlet temperature Tci of the cooling water flowing into the cooling tower 11 from the heat exchanger 3.

Δｔは，熱交換器３の仕様に基づいて定めるもので，熱交換器３に入る冷却水の温度と熱交換器３に入る冷水の温度との差，たとえば３〜５℃程度が望ましい。   Δt is determined based on the specifications of the heat exchanger 3, and is preferably a difference between the temperature of the cooling water entering the heat exchanger 3 and the temperature of the cooling water entering the heat exchanger 3, for example, about 3 to 5 ° C.

この実施形態によれば，フリークーリング能力Ｑの演算の元となる冷却水の入口温度Ｔciの代わりに，冷却水と熱交換関係にある冷水の入口温度Ｔeiの値を用いているので，冷水に温度変化が現れた段階，すなわち，冷却水の入口温度Ｔciの変化に反映される前に冷却水の入口温度Ｔciに相当する値を捕らえることができ，フリークーリング能力Ｑの変動をより速く捕らえ，フリークーリングの有効・無効の判定タイミングを的確に行うことができる。これにより，フリークーリングの有効・無効の判定タイミング遅れによる省エネルギーチャンスを失うのを防止できる。   According to this embodiment, since the value of the inlet temperature Tei of the cold water having a heat exchange relationship with the cooling water is used instead of the inlet temperature Tci of the cooling water which is the basis of the calculation of the free cooling capacity Q, The value corresponding to the cooling water inlet temperature Tci can be captured before the temperature change appears, that is, before being reflected in the change of the cooling water inlet temperature Tci, and the fluctuation of the free cooling capacity Q can be captured more quickly. It is possible to accurately determine the validity / invalidity of free cooling. As a result, it is possible to prevent losing an energy saving opportunity due to a delay in the determination timing of free cooling validity / invalidity.

本発明の一実施形態に係るフリークーリングシステムの系統図である。It is a systematic diagram of the free cooling system which concerns on one Embodiment of this invention. 本発明の一実施形態に係るフリークーリングシステムの制御ブロック図である。It is a control block diagram of the free cooling system which concerns on one Embodiment of this invention.

符号の説明Explanation of symbols

１ 第１冷却設備ユニット
２ 第２冷却設備ユニット
３ フリークーリング熱交換器
４ 供給側冷水ヘッダー
５ 戻り側冷水ヘッダー
６ 制御装置
７，８ 往き冷水管
９，１０ 戻り冷水管
１１，２１ 冷却塔
１２，２２ 冷凍機
１３，２３ 往き冷却水配管
１４，２４ 戻り冷却水配管
１５，２５ ポンプ
１６，２６ ポンプ
１７，１８，１９ 弁
３１ 冷却水側配管
３２ 冷水側配管
３３，３４，３５ 弁
４０ 大気湿球温度計測用のセンサー
４１，４２ 温度センサー DESCRIPTION OF SYMBOLS 1 1st cooling equipment unit 2 2nd cooling equipment unit 3 Free cooling heat exchanger 4 Supply side chilled water header 5 Return side chilled water header 6 Control device 7,8 Forward chilled water pipe 9,10 Return chilled water pipe 11,21 Cooling tower 12, 22 Refrigerator 13, 23 Outgoing cooling water piping 14, 24 Return cooling water piping 15, 25 Pump 16, 26 Pump 17, 18, 19 Valve 31 Cooling water side piping 32 Cold water side piping 33, 34, 35 Valve 40 Atmospheric wet bulb Sensor for temperature measurement 41, 42 Temperature sensor

Claims (3)

冷却塔，冷凍機を有する２基以上の冷凍設備ユニットと，任意の一基に設けられ，冷却塔の冷却水と被冷却側冷水と熱交換するフリークーリング熱交換器とを備えたフリークーリングシステムのフリークーリング有効・無効判定方法において，前記冷却塔のフリークーリング能力に基づいて，フリークーリング熱交換器による冷却塔冷却水と被冷却側冷水との熱交換を行うか否かを判定することを特徴とするフリークーリングシステムのフリークーリング有効・無効判定方法。   A free cooling system comprising two or more refrigeration equipment units having cooling towers and refrigerators, and a free cooling heat exchanger provided in any one unit for exchanging heat between the cooling water of the cooling tower and the cold water to be cooled. In the free cooling validity / invalidity determination method, it is determined whether or not to perform heat exchange between the cooling tower cooling water and the cooled side cooling water by the free cooling heat exchanger based on the free cooling capacity of the cooling tower. The free cooling effective / invalid determination method of the free cooling system which is the feature. 冷却塔，冷凍機を有する２基以上の冷凍設備ユニットと，任意の一基に設けられ，冷却塔の冷却水と被冷却側冷水と熱交換するフリークーリング熱交換器とを備えたフリークーリングシステムのフリークーリング有効・無効判定方法において，前記冷却塔の冷却水入口温度と大気湿球温度から求められるフリークーリング能力に基づいて，フリークーリング熱交換器による冷却塔冷却水と被冷却側冷水との熱交換を行うか否かを判定することを特徴とするフリークーリングシステムのフリークーリング有効・無効判定方法。   A free cooling system comprising two or more refrigeration equipment units having cooling towers and refrigerators, and a free cooling heat exchanger provided in any one unit for exchanging heat between the cooling water of the cooling tower and the cold water to be cooled. In the free cooling validity / invalidity determination method, the cooling tower cooling water by the free cooling heat exchanger and the cooled water on the cooled side are determined based on the free cooling capacity obtained from the cooling water inlet temperature and the atmospheric wet bulb temperature of the cooling tower. A method for determining whether or not a free cooling system is free cooling effective or invalid, characterized by determining whether or not to perform heat exchange. 前記冷却塔のフリークーリング能力は，冷却塔冷却水入口温度の代わりにフリークーリング熱交換器の被冷却側冷水入口温度から求めた値を用いることを特徴とする請求項１に記載のフリークーリングシステムのフリークーリング有効・無効判定方法。   The free cooling system according to claim 1, wherein the free cooling capacity of the cooling tower uses a value obtained from the cooled side cold water inlet temperature of the free cooling heat exchanger instead of the cooling tower cooling water inlet temperature. Free cooling valid / invalid judgment method.
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