Study of using a capillary tube in a heat pump dishwasher with transient heating

2016 ◽  
Vol 67 ◽  
pp. 1-9 ◽  
Author(s):  
Peder Bengtsson ◽  
Jonas Berghel
Keyword(s):  
Heat Pump ◽  
Capillary Tube ◽  
Transient Heating

Experimental Investigation on Flow Characteristic of Stepped Capillary Tube for Heat Pump Type Air Conditioner with R410A

2014 ◽  
Vol 960-961 ◽  
pp. 643-647
Author(s):  
Yan Sheng Xu
Keyword(s):  
Mass Flow Rate ◽  
Heat Pump ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Coefficient Of Performance ◽  
Tube Length ◽  
Air Conditioner ◽  
Capillary Tubes ◽  
Tube Assembly

A stepped capillary tube consisting of two serially connected capillary tubes with different diameters is invented to replace the conventional expansion device. The mass flow rate of refrigerant R410A in stepped capillary tubes with different size were tested. The model of stepped capillary tube is proposed, and its numerical algorithm for tube length and mass flow rate is developed. The experimental results show that the performance comparing between stepped capillary tube system and capillary tube assembly system, the cooling capacity is reduced by 0.3%, the energy efficiency ratio (EER) is equal to each other, the heating capacity is increased by 0.3%, the coefficient of performance (COP) is decreased by 0.3%. That is to say, the performance index of the two kinds of throttle mechanism is almost identical. It indicates that the stepped capillary tube can replace the capillary tube assembly in the R410A heat pump type air conditioner absolutely. The model is validated with experimental data, and the results show that the model can be used for sizing and rating stepped capillary tube.

Effect of Refrigerant Flow Control on the Heating Performance of a Variable-Speed Heat Pump Operating at Low Outdoor Temperature

2005 ◽  
Vol 127 (2) ◽  
pp. 277-286 ◽  
Author(s):  
Bong H. Kim ◽  
Dennis L. O’Neal
Keyword(s):  
Flow Control ◽  
Heat Pump ◽  
Performance Enhancement ◽  
Capillary Tube ◽  
Opening Angle ◽  
Variable Speed ◽  
Outdoor Temperature ◽  
Heating Performance ◽  
Heating Capacity ◽  
Expansion Valve

An experimental study was conducted to investigate the effect of electronic flow control on the performance of a variable-speed heat pump. A heat pump with two different expansion devices (capillary tube and electronic expansion valve) was tested in a psychrometric calorimeter over a range of outdoor temperatures from −15 to 7°C. Heat pump performance was first optimized with respect to charge for each expansion device through cycle-matching tests. Parametric tests also were conducted by changing compressor speed and opening angle for the electronic expansion valve at each outdoor temperature. The refrigeration cycle characteristics of the electronic valve were illustrated using pressure-enthalpy diagrams. Performance enhancement was also analyzed in terms of superheat, heating capacity, and energy efficiency ratio (EER). Comparison of the capillary tube and electronic valve indicated that the superheat significantly improved when using the electronic valve. Also, unit showed larger heating capacity and EER with the electronic valve than with the capillary tube except when the compressor speed was above 95 Hz. Enhancement of heating performance became larger as outdoor temperature decreased.

Capillary Tube as an Expansion Device in a CO2 (R744) Transcritical Heat Pump System

2015 ◽  
pp. 360-377
Author(s):  
Neeraj Agrawal ◽  
Souvik Bhattacharyya
Keyword(s):  
Critical Temperature ◽  
Heat Pump ◽  
Capillary Tube ◽  
Optimum Operating ◽  
Optimal Length ◽  
Pump System ◽  
Optimum Operating Condition ◽  
Heat Pump System ◽  
Expansion Valve ◽  
Vapour Compression

Natural refrigerants which are ecologically safe and were in use extensively in the pre-CFC era are witnessing a revival of CO2 (R744). Inherently being a low critical temperature (31.2 ?C) refrigerant, the CO2 cycle based system operates in transcritical mode offers an opportunity to obtain an optimum operating condition. Capillary tubes which are extensively used in small size vapour compression systems work very differently in a CO2 transcritical heat pump system. In this chapter it is described that installation of a capillary tube having an appropriately designed length replacing an expansion valve will result in a natural adjustment of the gas cooler pressure, so that the system balance always shifts to a favourable COP direction; this is contrary to the scepticism that exists on the capability of a capillary tube to attain the optimal pressure operation. There is an optimal length of capillary tube for a given diameter at which the heat pump runs optimally.

OS4-06 Study of the CO2-Heat Pump System Using Capillary Tube : Part 1 Steady State Characteristics of the Capillary Tube

2005 ◽  
Vol 2005.10 (0) ◽  
pp. 173-174
Author(s):  
Kazuki HARAGUCHI ◽  
Keisuke TAKAYAMA ◽  
Yoshiharu AMANO ◽  
Takumi HASHIZUME ◽  
Michio SASAKI
Keyword(s):  
Steady State ◽  
Heat Pump ◽  
Capillary Tube ◽  
Pump System ◽  
Heat Pump System

EXPERIMENTAL STUDY ON A NOVEL DEFROST CYCLE FOR AIR SOURCE HEAT PUMP

2010 ◽  
Vol 18 (01) ◽  
pp. 77-84 ◽  
Author(s):  
XIAN-MIN GUO ◽  
YA-JING WANG ◽  
WEN-CHENG FU ◽  
XIANG-CHENG TAO
Keyword(s):  
Experimental Study ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Capillary Tube ◽  
Experimental Results ◽  
Indoor Space ◽  
Mechanical Impact ◽  
Hot Gas ◽  
Switching Times ◽  
Air Source Heat Pump

On the basis of the hot-gas bypass defrost cycle, a new defrost method for air source heat pump is proposed. In the new defrost cycle, the outdoor heat exchanger is divided into two parts which are connected by a capillary tube. The front and rear parts of the heat exchanger are used as the evaporator and condenser respectively during defrosting, and can be defrosted orderly by using the four-way valve. The defrosting performance of the new cycle is investigated experimentally and the results are compared with that of the reverse-cycle defrost system. The experimental results indicate that the energy is used more efficiently in the new defrost cycle, therefore, the defrosting duration and losses are less than those of the reverse-cycle defrost system. Moreover, it does not extract heat from the indoor space during defrosting in terms of the new defrost cycle. Compared with the reverse-cycle defrost system, it is found that the switching times of the four-way valve in the new defrost system are the same, and the fluctuation of the discharge and suction pressures during the defrosting is much less than that in the reverse-cycle defrosting, hence, the mechanical impact on the system is much less.

Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycle

2007 ◽  
Vol 31 (11) ◽  
pp. 1016-1030 ◽  
Author(s):  
Neeraj Agrawal ◽  
Souvik Bhattacharyya
Keyword(s):  
Carbon Dioxide ◽  
Heat Pump ◽  
Capillary Tube ◽  
Tube Flow
Sign in / Sign up

Export Citation Format

Share Document