Optimal control of heat pump water heater-instantaneous shower using integrated renewable-grid energy systems

Abstract

Developing countries are grappling with energy and water insecurity, impelling governments to encourage end-users to conserve and efficiently consume these vital resources. With water heating being among the largest energy users in residential buildings, it is imperative that the efficiency and conservation of both energy and water are achieved. Heat pump water heaters (HPWHs) are a superior choice in efficiently providing domestic hot water. However, there are still challenges in their optimal operation and high initial cost in developing nations. Further, since they are normally centrally located in a house, there are water and associated energy losses during hot water conveyance to the end-use, as the cold water has to be poured away. This paper introduces an optimal control strategy of a hybrid HPWH and instantaneous shower powered using integrated renewable energy systems. This strategy has the potential to save 23.4% and 19 l of energy and water in a day respectively, while also promising lower energy and water bills to the end users. Further economic benefit can be achieved through the sale of excess renewable energy back to the grid through an appropriate feed-in tariff.

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“…However, with ever-rising population, the RES are not adequate to meet the daily demands of energy. To enhance the power generation hybrid systems are being designed and integrated with distributed generation systems [6] [7] [8].…”

Model predictive control of heat pump water heater-instantaneous shower powered with integrated renewable-grid energy systems

“…In this regard, the volume of hot water to be drawn can be estimated using the past hot water consumption and incorporated into a closed-loop MPC framework which would predict the future behaviour on-line [35]. In addition, HPWHs have a slow rate of heating water such that they cannot provide hot water in case of high demand [36]. Previous studies have also mainly concentrated on improving EE, though it is improtant to look at the energy-water nexus demand management [37].…”

“…This paper is an advancement of previously developed open loop optimal model used to operate both HPWH and instantaneous shower powered using integrated renewable energy systems [36]. A robust and economical closed-loop model predictive control strategy is introduced.…”

Optimal energy-water management in urban residential buildings through grey water recycling

“…For instance, the World Bank estimates the urban population in most African cities will double by 2030 [4]. Whereas developed nations have embarked on researching on energy-water nexus in urban areas [5,6,7], developing nations have been concentrating on either energy demand managemement [8,9,10,11,12], or water demand management [13,14,15,16], until recently when energy water nexus in buildings started gaining research interest [17,18]. Coordinated management of the two resources has the benefit of minimizing unaccounted indirect impact of one resource on the other [19].…”