scholarly journals 906 Performance Analysis of a C02 Heat Pump Water Heating System Using a Storage Tank With a Movable Insulating Plate : Influence of Daily Change in Hot Water Demand on System Performance

2010 ◽  
Vol 2010.85 (0) ◽  
pp. _9-6_
Author(s):  
Tetsushi MIYATA ◽  
Ryohei YOKOYAMA ◽  
Tetsuya WAKUI
Keyword(s):  
Performance Analysis ◽  
Heat Pump ◽  
Water Demand ◽  
System Performance ◽  
Storage Tank ◽  
Heating System ◽  
Hot Water ◽  
Water Heating ◽  
Daily Change

scholarly journals Numerical Analysis for Performance Evaluation of a Multi-Functional CO2 Heat Pump Water Heating System

2018 ◽  
Vol 8 (10) ◽  
pp. 1829 ◽  
Author(s):  
Ryohei Yokoyama ◽  
Masashi Ohkura ◽  
Takuya Nakamata ◽  
Tetsuya Wakui
Keyword(s):  
Heat Pump ◽  
System Performance ◽  
Storage Tank ◽  
Heating System ◽  
Functional System ◽  
Hot Water ◽  
System Efficiency ◽  
Water Heating ◽  
Perfect Mixing ◽  
Component Models

In recent years, CO2 heat pump water heating systems have been developed, and their performances have been enhanced while their functions have been expanded. In a multi-functional system, used for both hot water supply and bath heating, hot water retrieved from the top of a storage tank is returned to its bottom or side after heat exchange for bath heating, which destroys the stratified temperature distribution in the storage tank and degrades the system performance. In this paper, the performance of a multi-functional CO2 heat pump water heating system has been evaluated by numerical simulation. A system model was created by combining component models for a CO2 heat pump, mixing valves, a storage tank, a heat exchanger, and a bathtub. Partly, perfect mixing by hot water return was assumed in the component model for the storage tank, and its validity was verified through experiments. A performance analysis has been conducted under daily repeated hot water and bath heating demands, and the system performance was evaluated at a periodically steady state. As a result, the system efficiency and the volume of unused hot water in the multi-functional system decreased by 4.9% and 16.3%, respectively, as compared to those in the uni-functional system, when hot water returned to the bottom of the storage tank. When the position for hot water return is heightened, the system efficiency becomes higher than that in the uni-functional system, while the volume of unused hot water decreases furthermore.

Performance analysis of a CO2 heat pump water heating system under a daily change in a standardized demand

Energy ◽  
2010 ◽  
Vol 35 (2) ◽  
pp. 718-728 ◽  
Author(s):  
Ryohei Yokoyama ◽  
Tetsuya Wakui ◽  
Junya Kamakari ◽  
Kazuhisa Takemura
Keyword(s):  
Performance Analysis ◽  
Heat Pump ◽  
Heating System ◽  
Water Heating ◽  
Daily Change
Sign in / Sign up

Export Citation Format

Share Document