An investigation of drain-side wetting on the performance of falling film drain water heat recovery systems

Beentjes, Ivan; Manouchehri, Ramin; Collins, Michael R.

doi:10.1016/j.enbuild.2014.07.069

Cited by 23 publications

(12 citation statements)

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“…The CFR for a drain exchanger depends on a number of factors related to its geometrical and metallurgical properties. As an estimate, the CFR is between 4-8 L/min for pipes having a diameter of 5-10 cm [53]. In a field study, it was concluded that it initially takes five minutes for a HE to warm up when operating within the CFR limit [25].…”

Section: Operation Strategymentioning

confidence: 99%

A Key Review of Non-Industrial Greywater Heat Harnessing

2018

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Abstract:The ever-growing concerns about making buildings more energy efficient and increasing the share of renewable energy used in them, has led to the development of ultra-low carbon buildings or passive houses. However, a huge potential still exists to lower the hot water energy demand, especially by harnessing heat from waste water exiting these buildings. Reusing this heat makes buildings more energy-efficient and this source is considered as a third-generation renewable energy technology, both factors conforming to energy policies throughout the world. Based on several theoretical and experimental studies, the potential to harness non-industrial waste water is quite high.As an estimate about 3.5 kWh of energy, per person per day could be harnessed and used directly, in many applications. A promising example of such an application, are low temperature fourth generation District Heating grids, with decentralized sources of heat. At the moment, heat exchangers and heat pumps are the only viable options to harness non-industrial waste heat. Both are used at different scales and levels of the waste-water treatment hierarchical pyramid. Apart from several unfavourable characteristics of these technologies, the associated exergetic efficiencies are low, in the range of 20-50%, even when cascaded combinations of both are used. To tackle these shortcomings, several promising trends and technologies are in the pipeline, to scavenge this small-scale source of heat to a large-scale benefit.

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Section: Operation Strategymentioning

confidence: 99%

A Key Review of Non-Industrial Greywater Heat Harnessing

2018

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“…This phenomenon was observed in a previous study where low volumetric flow rates led to disturbances in the falling film, making the results non-repeatable [1]. This is why the values of ε r for different systems at tilt angles above 2 • are distributed over a range of values, as shown in Table 2 and Fig.…”

Section: Resultsmentioning

confidence: 72%

“…Steady state is achieved through stabilization of the inlet and outlet temperatures to less than 0.2 • C variation and the flow rate to less than 0.2 LPM variation. A detailed description of the test platform and its components are available in a previous publication by Beentjes et al [1].…”

Section: Methodsmentioning

confidence: 99%

“…The effectiveness of DWHR systems can be measured with an uncertainty of ±0.6% full scale using the test apparatus [1].…”

Section: Methodsmentioning

confidence: 99%

“…A DWHR system is most often a falling film counterflow heat exchanger consisting of small diameter copper pipes wrapped around a larger diameter copper drain pipe, as shown in Fig. 1 [1]. Heat transfer is from the warm drain-side water to the cold mains-side water, which recovers some of the otherwise wasted energy.…”

Section: Introductionmentioning

confidence: 99%

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Impact of small tilt angles on the performance of falling film drain water heat recovery systems

Manouchehri

Banister

Collins

2015

Energy and Buildings

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Life-cycle impacts of shower water waste heat recovery: case study of an installation at a university sport facility in the UK

She

Adeyeye

2017

Environ Sci Pollut Res

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Recovering heat from waste water discharged from showers to preheat the incoming cold water has been promoted as a cost-effective, energy-efficient, and low-carbon design option which has been included in the UK's Standard Assessment Procedure (SAP) for demonstrating compliance with the Building Regulation for dwellings. Incentivized by its carbon cost-effectiveness, waste water heat exchangers (WWHX) have been selected and incorporated in a newly constructed Sports Pavilion at the University of Brighton in the UK. This £2-m sports development serving several football fields was completed in August 2015 providing eight water- and energy-efficient shower rooms for students, staff, and external organizations. Six of the shower rooms are located on the ground floor and two on the first floor, each fitted with five or six thermostatically controlled shower units. Inline type of WWHX were installed, each consisted of a copper pipe section wound by an external coil of smaller copper pipe through which the cold water would be warmed before entering the shower mixers. Using the installation at Sport Pavilion as the case study, this research aims to evaluate the environmental and financial sustainability of a vertical waste heat recovery device, over a life cycle of 50 years, with comparison to the normal use of a PVC-u pipe. A heat transfer mathematical model representing the system has been developed to inform the development of the methodology for measuring the in-situ thermal performance of individual and multiple use of showers in each changing room. Adopting a system thinking modeling technique, a quasi-dynamic simulation computer model was established enabling the prediction of annual energy consumptions under different shower usage profiles. Data based on the process map and inventory of a functional unit of WWHX were applied to a proprietary assessment software to establish the relevant outputs for the life-cycle environmental impact assessment. Life-cycle cost models were developed and industry price book data were applied. The results indicated that the seasonal thermal effectiveness was over 50% enabling significant energy savings through heat recovery that led to short carbon payback time of less than 2 years to compensate for the additional greenhouse gas emissions associated with the WWHX. However, the life-cycle cost of the WWHX is much higher than using the PVC pipe, even with significant heat recovered under heavy usage, highlighting the need to adopt more economic configurations, such as combining waste water through fewer units, in order to maximize the return on investment and improve the financial viability.

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An investigation of drain-side wetting on the performance of falling film drain water heat recovery systems

Cited by 23 publications

References 1 publication

A Key Review of Non-Industrial Greywater Heat Harnessing

A Key Review of Non-Industrial Greywater Heat Harnessing

Impact of small tilt angles on the performance of falling film drain water heat recovery systems

Life-cycle impacts of shower water waste heat recovery: case study of an installation at a university sport facility in the UK

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