DIAGNOSTIC METHOD AND DIAGNOSTIC SYSTEM OF PERFORMANCE DETERIORATION OF WATER COOLING TYPE TURBO REFRIGERATING MACHINE

To provide a diagnostic method and a diagnostic system capable of quantitatively exhibiting the degree of staining of a heat transfer surface and obtaining a cost reduction effect according to measures such as addition of chemicals in a water-cooling type turbo refrigerating machine.SOLUTION: A data processing part 20 provided on a performance deterioration diagnostic system 1 calculates a real operation-time COP and operation-time logarithmic average temperature difference upon an operation of a refrigerating machine. Subsequently, the data processing part 20 calculates a normal-time COP when the water-cooling type turbo refrigerator 5 is in the normal-time state in such a case that a value of logarithmic average temperature difference is a value of operation-time logarithmic average temperature difference by using a correlation equation which exhibits a relation between a COP in the normal state free from the performance deterioration of the refrigerating machine due to staining of cooling water and the logarithmic average temperature difference. Subsequently, the data processing part 20 diagnoses the degree of staining of a heat transfer surface on a condenser on an inner part of the water cooling type turbo refrigerator 5 from a normalization COP as a ratio of the operation-time COP to the normal-time COP and displays results onto a display part 30 in a time series.SELECTED DRAWING: Figure 2 【課題】水冷式ターボ式冷凍機において、伝熱面汚れ度合いを定量的に示し、薬品添加等の対策によるコスト低減効果を得ることの可能な診断方法及び診断装置を提供する。【解決手段】本発明において、性能低下診断装置１に設けられたデータ処理部２０は、冷凍機の運転時における実際の運転時ＣＯＰ及び運転時対数平均温度差を算出する。続いて、データ処理部２０は、冷却水汚れによる冷凍機性能低下がない正常時状態でのＣＯＰと対数平均温度差との関係を示す相関式を用いて、対数平均温度差の値が運転時対数平均温度差の値である場合における、水冷式ターボ冷凍機５が正常時状態である場合の正常時ＣＯＰを算出する。続いて、データ処理部２０は、運転時ＣＯＰと正常時ＣＯＰとの比である正規化ＣＯＰから、水冷式ターボ冷凍機５の内部の凝縮器における伝熱面汚れ度合いを診断し、結果を表示部３０に時系列表示する。【選択図】図２