Experimental investigation of the effect of condenser channel dimensions on the condensation of air-steam mixture

The present study experimentally investigates the condensation of steam in the presence of air. In particular, the condensation efficiency has been examined which is defined by the ratio of heat released during the condensation process (the amount of latent heat) to the total heat extracted from the mixture of vapor and non-condensable gas (the sum of latent and sensible heats). The present experiment employs a cross-flow condenser where the air-steam mixture flow is cooled by dry airflow. The test setup is designed and built as three main parts, namely, process cycle, cooling cycle, and the test section. The process air (air-steam mixture) is operated in a closed cycle while the cooling air is operated in an open cycle. The process cycle is made of a process fan, a heater, and a humidifier. The test section is designed in such a way that the height and width of the channel are adjustable. In the test setup, flow rate, temperature, and humidity rates are controlled by the PLC system. Thus we investigate how the condensation efficiency is affected by various parameters such as (1) the operating conditions such as flow rates, and inlet temperatures and humidities for process and cooling flows and (2) the dimensions of the condenser channel. Results show that higher humidity, and higher condensation efficiency, as expected. The condensation efficiency is found to be generally less sensitive to the air-steam mixture flow rate. However, the efficiency decreases as the cooling airflow rate increases for a given humidity. This is believed to be due to the increasing diffusional resistance in the boundary layer as the cooling flow rate increases. When the channel height increases, the efficiency decreases at a lower cooling flow rate but appears to increase at a higher cooling flow rate except for the case with high humidity and a high mixture flow rate.