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In residential applications, an air-to-water CO 2 heat pump is used in combination with a domestic hot water storage tank, and the performance of this system is affected significantly not only by instantaneous ambient air and city water temperatures but also by hourly changes of domestic hot water consumption and temperature distribution in the storage tank. In this paper, the performance...
The potential to liberate steam production capacity for power generation has been assessed using actual energy consumption data and the recorded seasonal consumption fluctuations for a kraft pulp mill. The revenues from power production are compared with possible energy savings, achieved through enhancement of the process efficiency using an absorption heat pump (AHP). Bunker oil, wood bark and black...
A procedure for optimizing energy-management of a hospital complex is described, which, starting from hourly load diagrams, derived from the optimal design, allows the determination of the design and the running conditions of a trigeneration plant. The results obtained from the implementation of a mixed integer programming model, described here in detail, demonstrate how a trigeneration plant configuration...
In this study, a direct expansion solar-assisted heat pump water heater (DX-SAHPWH) with rated input power 750W was tested and analyzed. Through experimental research in spring and thermodynamics analysis about the system performance, some suggestions for the system optimization are proposed. Then, a small-type DX-SAHPWH with rated input power 400W was built, tested and analyzed. Through exergy analysis...
Concern for the environment has been steadily growing in recent years, and it is becoming more common to include environmental impact and pollution costs in the design problem along with construction, investment and operating costs.To economically respond to the global environmental problems ahead, progress must be made both on more sustainable technologies and on the design methodology, which needs...
Air-to-water heat pumps using CO 2 as a natural refrigerant have been developed and commercialized. They are expected to contribute to energy saving in residential hot water supply. The objective of the research is to analyze the performance of a water heating system composed of a CO 2 heat pump and a hot water storage tank by numerical simulation. In this paper, the system performance...
Due to rising fuel costs, the substantial price for CO 2 emissions and decreasing wind power costs, wind power might become the least expensive source of power for an increasing number of power systems. This poses the questions of how wind power might change optimal investments in other forms of power production and what kind of means could be used to increase power system flexibility in order...
Typically, a great deal of heat is wasted in the drainage systems of large-scale public shower facilities, such as those in schools, barracks, and natatoriums. This paper enhances a heat pump system used in public shower facilities for exhaust heat recovery. The system consists of three sections for exhaust heat recovery: solar energy collection system, drainage collection system, and heat pump system...
Geothermal district heating system design consists of two parts: heating system and piping network design. District heating system design and a case study for a university campus is given in Yildirim et al. [1] in detail. In this study, piping network design optimisation is evaluated based on heat centre location depending upon the cost and common design parameters of piping networks which are pipe...
This study aims at exploiting optimal configurations of technologies combined with co-generation theoretically based on a linear optimization model. With the objective function defining primary energy consumption to be minimized, optimal solutions are derived analytically. They describe the technological configurations as well as associated conditions depending on their final energy demand. An interesting...
In this paper, a mathematical model for steady-state simulation of transcritical CO 2 water-to-water heat pump system with an expander has been developed. It is used to simulate the performance of transcritical CO 2 system with CO 2 expander prototype. Simulated results are compared with experimental data to verify the accuracy of the simulation model. The comparison results...
The present work aims at evaluating the performance characteristics of a vapor compression heat pump (VCHP) for simultaneous space cooling (summer air conditioning) and hot water supply. In order to achieve this objective, a test facility was developed and experiments were performed over a wide range of evaporator water inlet temperature (14:26°C) and condenser water inlet temperature (22:34°C). R134a...
A novel cogeneration system was proposed and techno-economically investigated, consisting of a low-temperature geothermally-powered organic Rankine cycle (ORC) subsystem, an intermediate heat exchanger subsystem and a heat pump subsystem. The main purpose is to identify suitable working fluids (among 27 fluids with boiling point temperature ranging from −47.69 to 47.59°C) and optimized cycle parameters...
Thermally activated systems based on sorption cycles, as well as mechanical systems based on vapor compression/expansion are assessed in this study for waste heat recovery applications. In particular, ammonia-water sorption cycles for cooling and mechanical work recovery, a heat transformer using lithium bromide-water as the working fluid pair to yield high temperature heat, and organic Rankine cycles...
A numerical simulation of a plate contact-type isothermal heat pump dryer (HPD) is used to examine the energy efficiency improvement obtainable from this system compared with a conventional HPD. While we consider this system design to be entirely feasible, we are not aware of any existing practical applications of the design. The simulation incorporates a detailed plate, product and air flow model,...
Low exergy (LowEx) building systems create more flexibility and generate new possibilities for the design of high performance buildings. Instead of maximizing the barrier between buildings and the environment using thick insulation, low exergy systems maximize the connection to the freely available dispersed energy in the environment. We present implementations of LowEx technologies in prototypes,...
Since the fixed ejector cannot adjust the optimum high-side pressure, the adjustable ejector is designed and built based on a transcritical CO 2 heat pump system model results. The adjustable ejector is subjected to electrical pulses through the stepper motor which drives needle forward or backward movement to change the nozzle throat area for the optimum high-side pressure. Experimental investigation...
Geothermal energy has been successfully applied in many district heating systems. In order to promote better use of geothermal energy, it is important to analyze the operation strategy of geothermal heating system. This study proposes a comprehensive and systematic operation strategy for a geothermal step utilization heating system (GSUHS). Calculation models of radiator heating system (RHS), radiant...
This paper has shown the development of a theoretical model to determine the operating parameters and consumption of a domestic hot water (DHW) installation, which uses a direct-expansion solar assisted heat pump (DXSAHP) with refrigerant R-134a, a compressor with a rated capacity of 1.1kW and collectors with a total area of 5.6m2. The model results have been compared and validated the experimental...
Heat pumps, as a process recirculating environmental heat back into useful heat production, fit the environmental requirements of present global policy. They are very useful tools to reduce the need of fossil fuels in space heating and cooling. The government of the Republic of Korea has promoted the distribution of heat pump systems that apply geothermal energy, and has adopted regulation to prevent...
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