Abstract The US government has set a target of reducing CO2 emissions by 20% below the 2005 targets by the year 2020. Literature review reveals that residential buildings contribute over 20% of the total emissions mainly used for space heating, cooling, water heating and lighting. In hot humid climates, the concern is mainly for cooling and hot water that account for over 50% of the total resid...

In order to improve the overall efficiency of building energy usage, a grey water energy-recovery system, which adopted a multiple-function heat pump system, was proposed for domestic water heating, and space heating and cooling of buildings. A numerical model has been developed for investigation of annual energy and water consumptions of the proposed system and the conventional building energy...

According to recent technology road maps, system cost reductions and development of standardised plug-and-function systems are some of the most important goals for solar heating technology development. Retrofitting hot water boilers in single-family houses when installing solar collectors has the potential to significantly reduce both material and installation costs. Previous studies have inves...

In industrial applications, 90-150°C hot water needed during production processes is traditionally provided by fuelfired boilers. The use of fuel-fired boiler has a low efficiency of energy usage and potential danger of explosion. Byproduced 30-60°Cwaste water with large amount of energy is rejected to environment directly, which causes a great energy loss and thermal pollution. Seeking for a h...

This summer I had my first experience with something every homeowner dreads (and knows is coming eventually): a sudden puddle of water underneath the hot water heater. A local plumbing company quickly sent a technician out, who spared no time in pronouncing our current hot water heater dead. Then he explained that this company used flat-rate pricing: all jobs of a certain type cost the same fix...

Nowadays heat pump water heater becomes a very hot topic in hot water industry. However it still has many problems such as higher condensing temperature, large-scale operation conditions and lower COP in cold regions. Based on these problems, the paper presents a prototype assembled with a two-stage rotary compressor which can be used in cold regions. The working principle and the basic feature...

The control of heat exchange stations in district heating system is critical for the overall energy efficiency and can be very difficult due to high level of complexity. A conventional method is to control the equipment such that the temperature of hot water supply is maintained at a set-point that may be a fixed value or be compensated against the external temperature. This paper presents a no...

Vapor-dominated geothermal systems are proposed to originate by downward extension (by the "heat pipe" mechanism) into hot dry fractured rock above a large cooling igneous intrusion. High temperature zones found by drilling are shallow parts of the original hot dry rock where the penetration of the vapor reservoir was limited, and hot dry rock may extend under much of these reservoirs. An earli...

The paper is devoted to advanced control of a tubular heat exchanger with focus to energy savings. The controlled tubular heat exchanger (HE) was used for petroleum pre-heating by hot water. The controlled output was the measured temperature of the petroleum in the output stream and the control input was the volumetric flow rate of hot water. Two advanced control strategies were investigated in...