Determination of some discharge parameters of horizontally discharged cold-dense wastewaters

Abstract

Thermal pollution is defined as increase or decrease in temperature of an aquatic environment which may be ocean, lake or river by human influence. A common cause of thermal pollution is the use of water as a cooling and heating system by power plants, liquefied natural gas (LNG) re-gasification terminals and industrial manufacturers. One of the important sources of thermal effluents is cold water discharges, which are mainly originated from LNG re-gasification terminals from open cycle heating units. Cold water can be frequently discharged into coastal waters. Due to its high density, cold water discharge is a kind of negatively buoyant jet. Because of some undesired effects of cold water on receiving water species, should be discharged properly into the marine environment with a high level of initial dilution. Some discharge parameters of horizontally discharged cold-dense wastewater such as initial dilutions, impingement points were determined in a laboratory system using circular port in this study. To determine the behavior of the cold-dense wastewater (wastewater jet geometry) Rhodamine B as a colorant was added to the wastewater. A high-resolution camera was used to take snapshots of the colored cold-dense wastewater. Temperature changes (dilutions) in the cold-dense wastewater jet centerline were detected with sensitive thermal probes. To gain different densities, three discharge temperature differences were used as -3 degrees C, -5 degrees C and -7 degrees C. According to the results of this study, it was determined that the cold water discharges behaved like a negative buoyant jet. In addition, it was calculated that the averages of the normalized impingement point and initial dilution of the cold water were found 2.333 and 0.491, respectively.