Experimental Investigation of the Filling and Draining Processes of the Drainback System (Part 1)

Botpaev, Ruslan; Orozaliev, Janybek; Vajen, Klaus

doi:10.1016/j.egypro.2014.10.256

Cited by 7 publications

(12 citation statements)

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“…Measurement uncertainty, methodology of experiments, boundary conditions might be a reason, as they certainly play a role, but were partly specified in all the studies. The filling behaviour above the minimal "velocity" has been investigated in (Botpaev and Vajen, 2014b). They measured a deterioration of the deaeration process with reduction of the filling velocity.…”

Section: The Filling Processmentioning

confidence: 99%

“…5 on the right side of point C, as detailed in Botpaev and Vajen (2014b). The water completely fills the flow pipe and an underpressure is established at the top (about 60 kPa in this case).This vacuum pressure at the top can be calculated using Bernoulli's equation (Botpaev et al, 2014):…”

Section: The Operation Modementioning

confidence: 99%

“…Not susceptible to failure due to air Air in the solar collector loop is even mandatory for DBS, whereas it is often a typical problem for conventional pressurised solar thermal systems (Botpaev and Vajen, 2014b;Vögelin, 2014).…”

Section: Lower and Easier Maintenancementioning

confidence: 99%

“…Flow rate and pressure measurements of a DBS during the filling process are presented in Botpaev and Vajen (2014b) and transposed in Fig. 5.…”

Section: The Filling Processmentioning

confidence: 99%

“…"Levels outside these ranges signify potential problems" warns the ASHRAE. Botpaev and Vajen (2014b) investigated the phenomena at stakes and showed that the water flowing downward in the DB tank causes air entrainment due to vortex and splashing effects (Fig. 8).…”

Section: The Operation Modementioning

confidence: 99%

See 4 more Smart Citations

Drainback solar thermal systems: A review

et al. 2016

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Although solar drainback systems have been used for a long time, they are still generating questions regarding smooth functioning. This paper summarizes publications on drainback systems and compiles the current knowledge, experiences, and ideas on the technology. The collective research exhibits a lack of scientific publications dedicated to the drainback technology, however a significant number of patents have been published, detailing innovative technical solutions towards improvements and reliability. Based on the evaluation of drainback hydraulics, a detailed classification of this technology has been developed, with a brief description of each hydraulic typology. The operating modes have been split into three stages: filling, operation, and draining, which have been studied separately. A difference in the minimal filling velocities for a siphon development in the solar loop has been discovered in various reports. Specific features of the operation mode have been described. For the draining, existing mechanisms to initiate the emptying process have been identified and categorised. Finally, stateof-the-art hydraulic components for drainback systems have been established, with emphasis on their requirements. Based on those findings, the authors suggest potential future research paths in order to fill the knowledge gap and disseminate the drainback technology.

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Section: The Filling Processmentioning

confidence: 99%

Section: The Operation Modementioning

confidence: 99%

Section: Lower and Easier Maintenancementioning

confidence: 99%

“…Flow rate and pressure measurements of a DBS during the filling process are presented in Botpaev and Vajen (2014b) and transposed in Fig. 5.…”

Section: The Filling Processmentioning

confidence: 99%

Section: The Operation Modementioning

confidence: 99%

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Drainback solar thermal systems: A review

et al. 2016

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Solar Thermal Collectors

Reda¹

2016

Solar Assisted Ground Source Heat Pump Solutions

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Drain Back Systems in Laboratory and in Practice

et al. 2015

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Drain Back systems with ETC collectors are tested and analyzed in a Danish -Chinese cooperation project. Experiences from early work at DTU, with drain back, low flow systems, was used to design two systems: 1) One laboratory system at DTU. 2) One demonstration system in a single family house in Sorö Denmark. Detailed monitoring and modelling/validation of the system in the DTU lab is done, to be able to generalize the results, to other climates and loads by simulation and to make design optimizations. The advantage with drain back, low flow systems, is that the system can be made more simple with less components and that the performance can be enhanced. Also problems with long term degradation of glycol collector loops are totally avoided. A combination of the drain back and system expansion vessel was tested successfully. It is very important to achieve a continuous slope for the pipes in the collector loop to have a safe reliable operation. The components should also be designed and marked so that only one correct mounting option is possible, like forward and return pipes to/from the collector of slightly different sizes or color. Adapted installer education and training is a very important step to have success with drain back systems. Practices used in glycol systems may give serious failures.

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Experimental Investigation of the Filling and Draining Processes of the Drainback System (Part 1)

Cited by 7 publications

References 1 publication

Drainback solar thermal systems: A review

Drainback solar thermal systems: A review

Solar Thermal Collectors

Drain Back Systems in Laboratory and in Practice

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