- Title
- The DCMD-R as an energy efficient process
- Creator
- Nguyen, Minh H.; Bui, V. A.
- Relation
- 11th International Congress on Engineering and Food (ICEF2011). Proceedings of the 11th International Congress on Engineering and Food (ICEF 2011) (Athens 22-26 May 2011)
- Relation
- http://www.icef11.org/main.php?fullpaper
- Publisher
- Cosmosware
- Resource Type
- conference paper
- Date
- 2011
- Description
- Membrane Distillation is a thermal process for removing water from an aqueous feed solution across a hydrophobic porous membrane. The process driving force is generated by the temperature difference between the two streams involved. Operating at low temperatures, it is suitable for thermally sensitive products such as premium fruit juices, without using any chemical as in Osmotic Distillation. However, it has not yet been applied commercially as the energy utilisation is still high with little chance of energy recovery from the cold permeate stream The use of a heat pump specially designed to work with Direct Contact Membrane Distillation (DCMD) at low temperature should improve the energy efficiency. The objective of this project was to design a DCMD unit combined with a heat pump to generate the exact energy required from the cold water permeate to heat the thermally sensitive feed. As a result, a laboratory DCMD unit was integrated with a specially designed Refrigeration circuit as the patent pending DCMD-R (Refrigeration) system. Demonstrative trials showed its ability to carry out the concentration process with temperatures of the feed and permeate streams controlled close to their set points of 40 and 25 ºC, respectively. Electrical current and voltage were monitored to calculate the energy input. Mass flux was measured to work out the energy utilised during test runs on glucose concentration from 30% to 60% w/w. The laboratory DCMD-R unit delivered an average mass flux of up to 3.6 kg.m⁻².h⁻¹ over the whole operation. The success of the tests on the laboratory prototype DCMD-R system showed a vast improvement of energy efficiency when compared to that by the DCMD process alone. Despite the use of an inefficient compressor available, the DCMD-R system was able to increase the total energy efficiency from 43% to as high as 106%, a level that well surpassed the efficiency of 76% achieved by the single stage evaporation technique. Should a more efficient compressor have been used, say at a COP (coefficient of performance) of 4, an apparent energy efficiency of 160 to 200% could be within reach of the DCMD-R system. It implies that a DCMD-R system with the above apparent energy efficiency can achieve 0.5 - 0.62 tons of steam equivalent per ton of water evaporated, similarly to conventional multiple effect evaporation. A well designed and optimised DCMDR system is a serious alternative to all other concentration techniques as it requires low energy input, yet achieving high final concentration with minimal thermal effect on the final products.
- Subject
- Direct Contact Membrane Distillation; refrigeration; DCMD-R; energy efficiency; thermally sensitive liquids
- Identifier
- http://hdl.handle.net/1959.13/1064823
- Identifier
- uon:17673
- Identifier
- ISBN:9789608978935
- Language
- eng
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