scholarly journals EKSPERIMENTINIO ŠILUMOS SIURBLIO CIKLO VALDYMO ALGORITMO PAIEŠKA / EXPERIMENTAL STUDY OF THE HEAT PUMP CYCLE CONTROL ALGORITHM SEARCH

2019 ◽  
Vol 11 (0) ◽  
pp. 1-5
Author(s):  
Anton Frik ◽  
Dovydas Rimdžius ◽  
Tomas Kropas
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Ventilation System ◽  
Experimental Tests ◽  
Outdoor Air ◽  
Control Logic ◽  
Experimental Heat ◽  
Expansion Valve ◽  
Room Ventilation System ◽  
Compressor Power

This paper analyzes an experimental heat pump used for heat recovery in a mechanical room ventilation system. The aim of the work is to examine the operation, control logic of the heat pump and evaluate the possibilities of its operation modes, cycle control by outdoor air temperature. A review of scientific literature and experimental tests of the heat pump were performed to achieve this goal. Tests were performed in three stages, after each stage, according to the results obtained the heat pump stand was improved and experimental modes were adjusted. During the experiment, the tendencies of the heat pump freon and air involved in the heat exchange parameters are analyzed with different combinations of expansion valve positions and compressor power. Knowing these experimental characteristics, the extent to which the combination of these two controls can be used to efficiently control of the heat pump according to the outside air temperature is assessed. Based on the results of the research the heat pump control algorithms (depending on the variable outdoor air temperature) are prepared.

scholarly journals Experimental study on cascade heat pump dryer with a solar collector under low temperature outdoor air environment

2018 ◽  
Vol 22 (2) ◽  
pp. 993-1001 ◽  
Author(s):  
Sung Jang ◽  
Young Lee
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Solar Collector ◽  
Coefficient Of Performance ◽  
Outdoor Air ◽  
Temperature Range ◽  
Temperature Environment ◽  
Average Coefficient ◽  
Drying Efficiency ◽  
Drying Chamber

A heat pump dryer can save more energy than other dryers since its drying efficiency is 2-3 times higher than that of other types of dryers. However, the lower bound of evaporating temperature for an R134a heat pump cycle ranges from 5 to 10?C, when the outdoor air temperature closely approaches the evaporating temperature, it experiences reduced efficiency and ultimately becomes inoperable. To address this issue, a cascade heat pump dryer equipped with a solar collector was considered in order to examine the operability and efficiency of the heat pump cycle, depending on changes in the outdoor air temperature in wintertime. The changes in cascade cycles, depending on the temperature in a drying chamber, were also observed. The results showed that the average coefficient of performance (COP) of the cascade heat pump dryer was approximately 2.6 under the temperature range of ?10 to 20 ?C. An electrical heater whose COP is less than one should be used in that temperature range. It was also found that COP of the dryer increased by approximately 35% when using a solar collector under a low outdoor air temperature environment.

Experimental Investigation of Air-Source Heat Pump Heating System With a Novel Thermal Storage Refrigerant-Heated Panel

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Suola Shao ◽  
Huan Zhang ◽  
Shijun You ◽  
Yaran Wang
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Thermal Storage ◽  
Heating System ◽  
Economic Feasibility ◽  
Coefficient Of Performance ◽  
Total Annual Cost ◽  
Condensation Temperature ◽  
Outdoor Air ◽  
Air Source Heat Pump

Abstract In response to the triple crisis of energy–environment–economy (3Es), the air-source heat pump (ASHP) system is considered to be one of the most feasible candidates to upgrade the traditional high emission heating solutions. In this paper, a novel thermal storage refrigerant-heated panel (RHP) is proposed for the ASHP heating system. Experiments were conducted in a climate chamber to test the heating and defrosting performance of the system, the thermal performance of the RHP, the system energy efficiency, and the system economic feasibility. The results show that the heat flux of the RHP is as high as 625.5 W/m2 at a condensation temperature of 40 °C and an outdoor air temperature of −7 °C. Meanwhile, the system is demonstrated to be reliable and competitive with efficient thermal stability in heating conditions and comfortable indoor thermal in defrosting conditions. The coefficient of performance (COP) ranges from 2.2 to 4.0 when the outdoor air temperature changes from −12 °C to 7 °C in the tests. Meanwhile, the initial capital cost and the total annual cost of the proposed system are 430 USD and 203.1 USD, respectively, which is competitive in the distracted heating systems.

scholarly journals ENERGY EFFICIENCY IN CONSTANTA HARBOR- A THEORETICAL ASSESSMENT OF THE PERFORMANCE OF A HEAT PUMP FOR HEATING NEEDS, FOR A LESS POLLUTANT ADMINISTRATION OFFICE

2021 ◽  
Vol 2021 (2) ◽  
pp. 33-38
Author(s):  
FEIZA MEMET
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Fossil Fuels ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Electrical Heating ◽  
Outdoor Air ◽  
Heated Water ◽  
Air Temperatures ◽  
Discharge Temperature

In accordance with the present energetic exigencies, the energy consumption in port buildings is of a vital importance. From this perspective, heat pumps are less pollutant and more energy efficient options than the traditional heating technologies. This study focuses on an air source heat pump (ASHP), operating in an administration office located in Constanta harbor, Romania, in order to supply heated water during December of 2020. Electrically driven heat pumps are seen as a successful alternative to classical expensive heating means, such as electrical heating or the one based on fossil fuels combustion. Within this research, are investigated influences of the heated water temperatures and exterior air temperatures on the theoretical Coefficient of Performance, the compression ratio and the discharge temperature. The cycle is working with R134a, with 50C superheating and sub cooling. It will be considered that the heated water is supplied in the range (40-50) 0C, while the outdoor air temperature varies in the range (0-10) 0C. Obtained results show that the highest efficiency of the ASHP is obtained for the lowest value of the heated water temperature and for the highest value of the outdoor air temperature. This situation corresponds also to the good working of the compressor of the refrigeration plant, since are seen lowest values of the compression rate and the discharge temperature, as well. This means that the compressor do not consume high amounts of energy and the oil is not damaged because of high temperatures of the refrigerant vapors.

scholarly journals An analysis of effectiveness of air heat pump operation dependent on change of external air temperature

2021 ◽  
Vol 37 ◽  
pp. 24-30
Author(s):  
O. Shapoval ◽  
N.   Chepurna ◽  
M. Kirichenko
Keyword(s):  
Low Temperature ◽  
Water Temperature ◽  
Heat Pump ◽  
Air Temperature ◽  
Heat Carrier ◽  
Heat Pumps ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Outdoor Air ◽  
High Coefficient

Currently, air-to-water heat pumps are more widely used, which due to the high coefficient of performance reduce energy consumption and negative impact on the environment. They decrease the dependency on costs of energy resources. The work is devoted to solving the urgent problem of improving the efficiency of air heat pumps at low temperature of outdoor air in winter. One of the main problems of an air heat pump is the reduction of productivity when the outdoor air temperature decreases in winter. In this paper, the effectiveness of LG Therma V air-to-water heat pump to provide apartments with heating and hot water supply was analyzed. The heat pump is reversive, which can cool or heat a heat carrier. A four-way valve swithes the coolant flows between air exchangers. On the basis of the obtained results, plots of effectivness of the heat pump dependent on outdoor air temperature are built. It is shown that the effectiveness of the heat pump significantly depends not only on the outside temperature but also on the water temperature at the outlet of the heat pump. The use of heat pumps with a high coefficient of performance can significantly reduce energy costs. The most effective are low-temperature heating systems, in which the water temperature does not exceed 45 °C. The example is floor heating, which requires very low temperature of the floor surface – up to 30 °C. At outdoor air temperature not less than milnus 7 °C the heat pump is effective at higher temperature off heat carrier at output – up to 55 °C. To provide the uninterrupted heat supply, an additional air heater is included. It covers heat load during defrosting and very low outdoor air temperature. On the basis of the conducted researches, the directions of the further experimental and field researches are planned.

scholarly journals ENERGY CONVERSION MODES DEPENDING ON THE OUTDOOR TEMPERATURE FOR AN AIR HANDLING UNIT WITH A HEAT PUMP

2020 ◽  
Author(s):  
Anton Frik ◽  
Vytautas Martinaitis ◽  
Juozas Bielskus
Keyword(s):  
Energy Conversion ◽  
Heat Pump ◽  
Air Temperature ◽  
Ambient Air ◽  
Operating Efficiency ◽  
Outdoor Air ◽  
Characteristic Energy ◽  
Flow Rates ◽  
Air Handling Unit ◽  
Wide Range

Modern air handling units (AHU) are increasingly finding solutions in which the main energy transformers are an air heat pump (HP) and a heat recovery exchanger (HRE). The energy conversion modes of such devices are constantly changing in accordance with the constant change on the state of the outdoor air (temperature, humidity). Flexibility, being able to respond to ever-changing ambient air parameters, is an important feature of energy transformation component mode control. The overall seasonal efficiency of the air handling unit depends on this. In this work, a thermodynamic analysis of the characteristic energy transformations of the air handling unit is performed, linking the outdoor and ventilated indoor air and HP refrigerant states, flow rates and component loads. Such parametric analysis with respect to the changing outdoor air temperature allowed to clearly reveal, through various indicators, the influence of the individual components on the operating efficiency of the air handling unit. Combinations of parameters have been obtained that enable the selection of the optimal control concept for the energy conversion mode of the components in the air handling unit (component loads, fluids state parameters and flow rates) over a wide range of outdoor air temperatures.

scholarly journals Seasonal COP of an Air-to-Water Heat Pump when Using Predictive Control Preferring Power Production from Renewable Sources in the Czech Republic

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3236
Author(s):  
Jiří Pospíšil ◽  
Michal Špiláček ◽  
Pavel Charvát
Keyword(s):  
Czech Republic ◽  
Wind Power ◽  
Heat Pump ◽  
Air Temperature ◽  
Predictive Control ◽  
Power Production ◽  
Outdoor Air ◽  
Renewable Sources ◽  
The Czech Republic ◽  
Study Results

The paper presents a parametric study evaluating the effects of various predictive controls on the operating parameters of heat pumps. The heat pump represents a significant power appliance in the residential sector. Its connection to the heat accumulator creates a system with considerable potential to control electricity consumption according to the needs of the electricity grid. The air-water heat pump is considered in this study. A predictive control is used for priority operation of the heat pump at periods of peak power production from renewable sources. The following were tested as the parameters of predictive control: outdoor air temperature, photovoltaic power production and wind power production. The combination of photovoltaic and wind power production was also tested. A parametric analysis considering different sizes for the thermal accumulator and the heating capacity of the heat pump were proposed. The benefits of predictive control are evaluated based on historical records of meteorological data from 2015 to 2018 in the city of Brno, Czech Republic. The data on the historical development of the real electrical energy production from renewable sources in the Czech Republic are used for regulation control in a monitored period. The main comparison parameter is the heat pump seasonal coefficient of performance (SCOP). From the carried out study results, an increase in SCOP by 14% was identified for priority operation of heat pump (HP) at periods with highest outdoor air temperature. Priority operation of HP at periods with peak photovoltaic (PV) production increased SCOP by 10.25%. A decrease in SCOP only occurred in case with priority operation of HP at peak production of wind power plants. Increasing the size of the accumulator contributes to an increase in SCOP in all assessed modifications of predictive control.

Study on Change Regularity of Air Temperature Underground Tunnel Based on Intermittent Operating of Heat Pump

2011 ◽  
Vol 90-93 ◽  
pp. 1671-1674
Author(s):  
Yong An Li ◽  
Ya Nan Gao ◽  
Zong Jin Yang ◽  
Xue Lai Liu
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Soil Temperature ◽  
Heat Pump ◽  
Air Temperature ◽  
Transfer Model ◽  
Unsteady State ◽  
Outdoor Air ◽  
One Dimensional ◽  
Remarkable Effect

In this paper, based on the analysis of strata soil temperature variation, the DeST software is used to simulate changes of outdoor air parameters under typical meteorological year in Jinan. One-dimensional unsteady state soil air heat transfer model is regarded as the research object, this paper theoretically studies export air temperature change rules for the whole year under tunnel intermittent running condition. The results show that the tunnel plays a preheating role for outdoor air in winter and the cold role in summer, which provides a good cold、heat source conditions for the application of air source system based on the tunnel wind, especially the most hot and cold day throughout the year, the system has a remarkable effect.

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