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A mathematical model to predict the thermosiphon flow rate of a single slope solar still coupled with evacuated tube collector and its validation with experiments is presented in this paper. The objective of this experimental investigation is to determine the significance of thermosiphon flow rate and its impact on the fresh water yield during nocturnal conditions. The coupled system operates under thermosiphon through a heat exchanger placed within the basin water. The work was extended to study the influence of ambient temperature on thermosiphon head generated in the system. It was interesting to observe that higher temperature of water in Evacuated Tubular Collector (ETC) tank did not contribute to better flow rate at the inlet of the siphon circuit for varying exit temperatures. Numerical analysis was performed to determine the thermosiphon flow rate and it has good agreement with the experimental results.

AbstractA new desalination method was proposed in this work, utilizing low-grade waste heat from the power plant, allowing co-generation of fresh water with electricity. The desalination system analysed in this study makes use of simple concepts, such as Torricelli vacuum, flash evaporation and siphon effect, to reduce the overall operating power consumption of the plant. An experimental plant has been built and tested in an existing thermal power plant at Chennai, India. The plant utilized the warm saline reject water from the power plant condenser to feed the evaporator without using a separate feed water pump. The amount of freshwater produced by this plant is nearly 1/200 times of the sea water supplied for the available temperature gradient of 8.7°C. It is a low-cost system when compared with conventional desalination technologies, with energy consumption per unit volume estimated at 2.62 kWh/m3of fresh water generated. It operates at low temperatures, low pressure conditions and produces fresh water of excellent quality. The successful operation of the plant has provided valuable experience and information related to the behaviour of the proposed desalination system.

A new desalination method was proposed in this work, utilizing low-grade waste heat from the power plant, allowing co-generation of fresh water with electricity. The desalination system analysed in this study makes use of simple concepts, such as Torricelli vacuum, flash evaporation and siphon effect, to reduce the overall operating power consumption of the plant. An experimental plant has been built and tested in an existing thermal power plant at Chennai, India. The plant utilized the warm saline reject water from the power plant condenser to feed the evaporator without using a separate feed water pump. The amount of freshwater produced by this plant is nearly 1/200 times of the sea water supplied for the available temperature gradient of 8.7°C. It is a low-cost system when compared with conventional desalination technologies, with energy consumption per unit volume estimated at 2.62 kWh/m3of fresh water generated. It operates at low temperatures, low pressure conditions and produces fresh water of excellent quality. The successful operation of the plant has provided valuable experience and information related to the behaviour of the proposed desalination system.

The Backward Bent Duct Buoy (BBDB) is a wave energy converter which works on the principle of the Oscillating Water Column theory. The air displaced due to the rising and falling water surface in the oscillating water column is used to drive an electric machine to generate power. A physical model of the prototype BBDB with a geometric scale of 1:8 made of acrylic glass of size 412 × 280 × 255 mm was tested in the wave flume at the Centre for Water Resources laboratory, Anna University to determine the pneumatic efficiency of BBDB. The pneumatic efficiency, which is the ratio of output power of the displaced air to the input power due to waves, is primarily dependent on the amplitude of oscillation of the water column in the vertical air chamber. The effect of increasing the length of the horizontal duct on pneumatic efficiency has been studied. It was found that the duct length affects the primary conversion efficiency considerably and longer ducts may not necessarily improve the efficiency. It was observed that the BBDB model with the duct length of 412 mm shows better primary conversion efficiency of 5.3% and the area of the orifice opening also has an effect on the pneumatic efficiency.

A method of desalination that takes advantage of temperature differences within the ocean is helping to supply a remote island with drinking water by means of a cleverly designed and constructed deepwater pipeline and the trestle that supports it.

Conventional desalination technologies like multi stage flashing, multi-effect desalination (MED) using steam as motive fluid can be made sustainable by obtaining the motive steam from solar thermal systems. In this study, a transient simulation has been performed to determine the dissimilitude in pressure drop and dryness fraction, of working fluid in absorber tube due to variation in solar irradiance. A one-dimensional (1D) mathematical model has been developed using matlab for assessing the thermal performance and heat transfer characteristics of a direct steam generating (DSG) parabolic trough collector (PTC) system. It was observed that maximum pressure drop does not occur at maximum quality indicating the working conditions impair the system performance. The developed model was used to overcome this by varying both pressure and mass flowrate of working fluid in accordance to the radiation, results indicated reduction in pressure drop during the same time period for the same exit quality.