Cool Steam Method for Desalinating Seawater

Cool steam is an innovative distillation technology based on low-temperature thermal distillation (LTTD), which allows obtaining fresh water from non-safe water sources with substantially low energy consumption. LTTD consists of distilling at low temperatures by lowering the working pressure and making the most of low-grade heat sources (either natural or artificial) to evaporate water and then condensate it at a cooler heat sink. To perform the process, an external heat source is needed that provides the latent heat of evaporation and a temperature gradient to maintain the distillation cycle. Depending on the available temperature gradient, several stages can be implemented, leading to a multi-stage device. The cool steam device can thus be single or multi-stage, being raw water fed to every stage from the top and evaporated in contact with the warmer surface within the said stage. Acting as a heat carrier, the water vapor travels to the cooler surface and condensates in contact with it. The latent heat of condensation is then conducted through the conductive wall to the next stage. Net heat flux is then established from the heat source until the heat sink, allowing distilling water inside every parallel stage.

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A Dual-Source Organic Rankine Cycle (DORC) for Improved Efficiency in Conversion of Dual Low- and Mid-Grade Heat Sources

ASME 2009 3rd International Conference on Energy Sustainability, Volume 1 ◽

10.1115/es2009-90220 ◽

2009 ◽

Cited By ~ 3

Author(s):

F. David Doty ◽

Siddarth Shevgoor

Keyword(s):

Heat Source ◽

Heat Input ◽

Temperature Limit ◽

Working Fluid ◽

Inlet Temperature ◽

Low Grade ◽

Heat Sources ◽

Reaction Products ◽

Pinch Point ◽

Low Grade Heat

Detailed thermodynamic and systems analyses show that a novel hybrid cycle, in which a low-grade (and low-cost) heat source (340 K to 460 K) provides the boiling enthalpy and some of the preheating while a mid-grade source (500 K to 800 K) provides the enthalpy for the final superheating, can achieve dramatic efficiency and cost advantages. Four of the more significant differences from prior bi-level cycles are that (1) only a single expander turbine (the most expensive component) is required, (2) condenser pressures are much higher, (3) the turbine inlet temperature (even with a low-grade geothermal source providing much of the energy) may be over 750 K, and (4) turbine size is reduced. The latent heat of vaporization of the working fluid and the differences in specific heats between the liquid and vapor phases make full optimization (approaching second-law limits) impossible with a single heat source. When two heat sources are utilized, this problem may be effectively solved — by essentially eliminating the pinch point. The final superheater temperature must also be increased, and novel methods have been investigated for increasing the allowable temperature limit of the working fluid by 200 to 350 K. The usable temperature limit of light alkanes may be dramatically increased by (1) accommodating hydrogen evolution from significant dehydrogenation; (2) periodically or continually removing undesired reaction products from the fluid; (3) minimizing the fraction of time the fluid spends at high temperatures. Detailed simulation results are presented for the case where (1) the low-grade heat source (such as geothermal) is 400 K and (2) the mid-grade Concentrated Solar Power (CSP) heat source is assumed to be 720 K. For an assumed condensing temperature of 305 K and working fluid flow rate of 100 kg/s, preliminary simulations give the following: (1) low-grade heat input is 25 MWT; (2) mid-grade heat input is 24 MWT; (3) the electrical output power is 13.5 MWE; and (4) the condenser rejection is only 35 MWT. For comparison, with a typical bi-level ORC generating similar power from this geothermal source alone, the low-grade heat requirement would be ∼100 MWT.

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Investigations of prototype ejection refrigeration system driven by low grade heat

E3S Web of Conferences ◽

10.1051/e3sconf/20187003002 ◽

2018 ◽

Vol 70 ◽

pp. 03002 ◽

Cited By ~ 10

Author(s):

Dariusz Butrymowicz ◽

Jerzy Gagan ◽

Kamil Śmierciew ◽

Michał Łukaszuk ◽

Adam Dudar ◽

...

Keyword(s):

Experimental Investigation ◽

Heat Source ◽

Air Conditioning ◽

Thermal Capacity ◽

Low Grade ◽

Heat Sources ◽

Refrigeration System ◽

Gas Emission ◽

Low Grade Heat ◽

System Operating

One of possibilities of reduction of F-gas emission is application of low grade heat to drive the refrigeration systems as well as application of natural or low warming impact working fluids. The own experimental investigation of the ejection refrigeration system operating with refrigerant R-1234zeE are presented and discussed. The system is driven with low grade heat source of temperature below 70°C and thermal capacity approximately 90 kW. The experiments covered the effect of condensation, evaporation and generation temperatures on the capacity and thermal efficiency of the ejection refrigeration system operating for the air-conditioning purposes. Obtained results demonstrated that the proposed system may be thought as the promising heat driven refrigeration system with application of low grade motive heat sources.

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A New Targeting Method for Combined Heat, Power and Desalinated Water Production in Total Site

Volume 6: Energy, Parts A and B ◽

10.1115/imece2012-88885 ◽

2012 ◽

Author(s):

Mohammad Hasan Khoshgoftar Manesh ◽

Hooman Ghalami ◽

Sajad Khamis Abadi ◽

Majid Amidpour ◽

Mohammad Hosein Hamedi

Keyword(s):

Heat Source ◽

Waste Heat ◽

Carbon Dioxide Emission ◽

Cooling Water ◽

Low Grade ◽

Multi Stage ◽

Utility Systems ◽

Utility System ◽

Multiple Effect Distillation ◽

Low Grade Heat

Low-grade heat is available in large amounts across process industry from temperatures of 30 °C to 250 °C as gases (e.g. flue gas) and/or liquids (e.g. cooling water). Various technologies are available for generating, distributing, utilizing and disposing of low grade energy. Also, conventional desalination technologies are energy intensive and if the required energy hails from fossil fuel source, then the freshwater production will contribute to carbon dioxide emission and consequently global warming. In this regard, low grade heat source can be very useful to provide energy to the heat sink by upgrading low-grade energy (e.g. low pressure steam). The upgrade of low grade heat can be carried out by desalination technologies by recovering waste heat from various sources. The steam network of site utility system has a suitable potential for production of low grade heat. Estimation of cogeneration potential prior to the design of the central utility system for site utility systems, is vital to set targets on site fuel demand as well as heat and power production. So, a new cogeneration targeting model has been developed for integration of steam desalination systems and site utility of process plant. The new procedure to find optimal integration has been proposed based on new cogeneration targeting. In this paper, evaluation of coupling different desalination systems which includes multi-stage flash (MSF), multiple effect distillation (MED), membrane reverse osmosis (RO), and hybrid (MSF/MED-RO) to steam network of site utility system with have been considered. The integration of desalination systems to a low grade heat source has been performed using proposed cogeneration targeting method. In addition, a modified Site Utility Grand Composite Curve (SUGCC) diagram is proposed and compared to the original SUGCC. A steam network of process utility system has been considered as a case study.

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