scholarly journals EXPERIMENTAL ANALYSIS OF A HEAT PUMP ASSISTED RECUPERATIVE AIR DEHUMIDIFIER

2004 ◽  
Vol 3 (1) ◽  
Author(s):  
C. A. B. Pereira ◽  
R. H. Pereira ◽  
R. P. Marques ◽  
J. A. R. Parise ◽  
J.R. Sodré
Keyword(s):  
Water Vapor ◽  
Energy Consumption ◽  
Heat Pump ◽  
Experimental Analysis ◽  
Open Circuit ◽  
Dew Point ◽  
Air Stream ◽  
Controlling Parameter ◽  
Experimental Apparatus ◽  
Low Humidity

This paper describes the experimental analysis of a heat pump assisted recuperative air dehumidifier. The system consisted of an air-to-air vapor compression heat pump, coupled to the air ducting. Dehumidification was generated by reduction of the air temperature through the evaporator below the dew point, and thus promoting the condensation of the water vapor. Moist air was then warmed up in the condenser, resulting in a lowtemperature low-humidity air stream. Low energy consumption values are achieved in such systems as the latent heat of the water vapor acts as the heat pump own heat source. Occasionally, the compressor heat is also recoverable. The innovative feature of the present analysis was the introduction of an air-to-air plate recuperator, to further promote dehumidification, yet at the expense of greater compressor energy consumption. An experimental apparatus was constructed to perform comparative tests of the dehumidifier operating with and without the recuperator. A closed air circuit was employed, with the air mass flow rate as the controlling parameter of the experiment. Tests were also carried out with an open circuit.

scholarly journals EXPERIMENTAL ANALYSIS OF A HEAT PUMP ASSISTED RECUPERATIVE AIR DEHUMIDIFIER

2004 ◽  
Vol 3 (1) ◽  
pp. 56
Author(s):  
C. A. B. Pereira ◽  
R. H. Pereira ◽  
R. P. Marques ◽  
J. A. R. Parise ◽  
J.R. Sodré
Keyword(s):  
Water Vapor ◽  
Energy Consumption ◽  
Heat Pump ◽  
Experimental Analysis ◽  
Open Circuit ◽  
Dew Point ◽  
Consumption Values ◽  
Air Stream ◽  
Controlling Parameter ◽  
Low Humidity

This paper describes the experimental analysis of a heat pump assisted recuperative air dehumidifier. The system consisted of an air-to-air vapor compression heat pump, coupled to the air ducting. Dehumidification was generated by reduction of the air temperature through the evaporator below the dew point, and thus promoting the condensation of the water vapor. Moist air was then warmed up in the condenser, resulting in a lowtemperature low-humidity air stream. Low energy consumption values are achieved in such systems as the latent heat of the water vapor acts as the heat pump own heat source. Occasionally, the compressor heat is also recoverable. The innovative feature of the present analysis was the introduction of an air-to-air plate recuperator, to further promote dehumidification, yet at the expense of greater compressor energy consumption. An experimental apparatus was constructed to perform comparative tests of the dehumidifier operating with and without the recuperator. A closed air circuit was employed, with the air mass flow rate as the controlling parameter of the experiment. Tests were also carried out with an open circuit.

scholarly journals The stability and calibration of water vapor isotope ratio measurements during long-term deployments

2015 ◽  
Vol 8 (5) ◽  
pp. 5425-5466 ◽  
Author(s):  
A. Bailey ◽  
D. Noone ◽  
M. Berkelhammer ◽  
H. C. Steen-Larsen ◽  
P. Sato
Keyword(s):  
Water Vapor ◽  
Concentration Dependence ◽  
Hydrological Cycle ◽  
Dew Point ◽  
Vapor Concentration ◽  
Mauna Loa ◽  
Laser Absorption ◽  
Low Humidity ◽  
The Stability

Abstract. With the recent advent of commercial laser absorption spectrometers, field studies measuring stable isotope ratios of hydrogen and oxygen in water vapor have proliferated. These pioneering analyses have provided invaluable feedback about best strategies for optimizing instrumental accuracy, yet questions still remain about instrument performance and calibration approaches for multi-year field deployments. With clear scientific potential for using these instruments to carry out long-term monitoring of the hydrological cycle, this study examines the long-term stability of the isotopic biases associated with three cavity-enhanced laser absorption spectrometers – calibrated with different systems and approaches – at two remote field sites: Mauna Loa Observatory, Hawaii, USA, and Greenland Environmental Observatory, Summit, Greenland. The analysis pays particular attention to the stability of measurement dependencies on water vapor concentration and also evaluates whether these so-called concentration-dependences are sensitive to statistical curve-fitting choices or measurement hysteresis. The results suggest evidence of monthly-to-seasonal concentration-dependence variability – which likely stems from low signal-to-noise at the humidity-range extremes – but no long-term directional drift. At Mauna Loa, where the isotopic analyzer is calibrated by injection of liquid water standards into a vaporizer, the largest source of inaccuracy in characterizing the concentration-dependence stems from an insufficient density of calibration points at low humidity. In comparison, at Greenland, the largest source of inaccuracy is measurement hysteresis associated with interactions between the reference vapor, generated by a custom dew point generator (DPG), and the sample tubing. Nevertheless, prediction errors associated with correcting the concentration-dependence are small compared to total measurement uncertainty. At both sites, a dominant source of uncertainty is instrumental precision at low humidity, which cannot be reduced by improving calibration strategies. Challenges in monitoring long-term isotopic drift are also discussed in light of the different calibration systems evaluated.

scholarly journals Modeling the dynamic behavior of a droplet evaporation device for the delivery of isotopically calibrated low-humidity water vapor

2020 ◽  
Author(s):  
Erik Kerstel
Keyword(s):  
Water Vapor ◽  
Dynamic Behavior ◽  
Quantitative Description ◽  
Water Concentration ◽  
Droplet Surface ◽  
Dry Air ◽  
Air Stream ◽  
Pressure Water ◽  
Low Humidity ◽  
Water Isotope

Abstract. A simple model is presented that gives a quantitative description of the dynamic behavior in terms of water concentration (humidity) and isotope ratios of a low-humidity water vapor generator. The generator is based on the evaporation of a nL-droplet produced at the end of syringe needle by balancing the inlet water flow and the evaporation of water from the droplet surface into a dry air stream. The humidity level is adjusted by changing the speed of the high-precision syringe pump and, if needed, the dry air flow. The generator was developed specifically for use with laser-based water isotope analyzers in Antarctica, and recently described in Leroy-Dos Santos et al. (2020). Apart from operating parameters such as temperature, pressure, water and dry air flows, the model has as "free" input parameters the water isotope fractionation factors and the evaporation rate. We show that the experimental data constrain these parameters to physically realistic values that are in reasonable to good agreement with literature values where available.

Performance Evaluations of Extracting Water From Dry Air Using Multi-Stage Desiccant Wheels and Vapor Compression Cycle

2019 ◽  
Author(s):  
Rang Tu ◽  
Lanbin Liu
Keyword(s):  
Water Vapor ◽  
Energy Consumption ◽  
High Temperature ◽  
Low Temperature ◽  
Rural Areas ◽  
Waste Heat ◽  
Dew Point ◽  
Solid Adsorbent ◽  
Multi Stage ◽  
Condense Water

Abstract A water extraction device that takes water from air in dry area is proposed. This device is designed to meet domestic water demand in remote rural areas, where the climate is dry and fresh water is scarce. The device can be driven effectively by low-temperature waste heat and has the characteristics of large daily water production, low energy consumption per unit of water and high water quality. Because the moisture content of air in dry area is very low, the effect of direct condensation is limited. Solid adsorbent is able to adsorb water vapor from air at a low temperature and release water vapor at under high temperature, which can be used for water extracting from air. To improve its performance under dry circumstances, the key technical point of this device is to use solid adsorbent to collect water vapor from other air to raise its dew point temperature, and then use high temperature cold source to condense water vapor from it. In this paper, configurations of the solid adsorption are proposed, which can be driven with low regeneration temperature under the same humidity increasing amount. This device uses multi-stage desiccant wheels to realize humid increasing. Desiccant wheel can be driven with high temperature to take water vapor from dehumidification air and release water vapor to regeneration air. The multi-stage configuration is good for the reduction of regeneration temperature, making applications of low temperature waste heat form heat pumps possible. Then, influencing factors of water extracting rate are analyzed. The influencing of regeneration temperature, humid reduction amount of the humidified air and cooling and heating systems, etc., are analyzed. Last, air handling processes considering cold and heat sources are recommended to reduce energy consumption. The heat pump driven scenarios are discussed in particular. Through optimization, the water extracting rate can be increased and energy consumption per unit of water can be reduced. At present, this paper only studies air water extracting processes and thermal processes, and does not involve structure of the device, water purification and power consumption of fans, etc.

Saving Primary Energy Consumption Through Exergy Analysis of Combine Distillation and Power Plant

2012 ◽  
Vol 9 (2) ◽  
pp. 65
Author(s):  
Alhassan Salami Tijani ◽  
Nazri Mohammed ◽  
Werner Witt
Keyword(s):  
Energy Consumption ◽  
Power Plant ◽  
Heat Pump ◽  
Heat Recovery ◽  
Energy Savings ◽  
Primary Energy ◽  
Heat Pumps ◽  
Saturated Steam ◽  
Distillation Unit ◽  
Primary Energy Consumption

Industrial heat pumps are heat-recovery systems that allow the temperature ofwaste-heat stream to be increased to a higher, more efficient temperature. Consequently, heat pumps can improve energy efficiency in industrial processes as well as energy savings when conventional passive-heat recovery is not possible. In this paper, possible ways of saving energy in the chemical industry are considered, the objective is to reduce the primary energy (such as coal) consumption of power plant. Particularly the thermodynamic analyses ofintegrating backpressure turbine ofa power plant with distillation units have been considered. Some practical examples such as conventional distillation unit and heat pump are used as a means of reducing primary energy consumption with tangible indications of energy savings. The heat pump distillation is operated via electrical power from the power plant. The exergy efficiency ofthe primary fuel is calculated for different operating range ofthe heat pump distillation. This is then compared with a conventional distillation unit that depends on saturated steam from a power plant as the source of energy. The results obtained show that heat pump distillation is an economic way to save energy if the temperaturedifference between the overhead and the bottom is small. Based on the result, the energy saved by the application of a heat pump distillation is improved compared to conventional distillation unit.

DETERMINING THE PROFITABILITY OF GREENHOUSE ELECTROTECHNOLOGIES: A MODELING APPROACH

HortScience ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 249a-249
Author(s):  
Eric A. Lavoie ◽  
Damien de Halleux ◽  
André Gosselin ◽  
Jean-Claude Dufour
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Water System ◽  
Heat Pumps ◽  
Hot Water ◽  
Pump System ◽  
Heat Pump System ◽  
Artificial Lighting ◽  
Hot Air ◽  
Marketable Fruit

The main objective of this research was to produce a simulated model that permitted the evaluation of operating costs of commercial greenhouse tomato growers with respect to heating methods (hot air, hot water, radiant and heat pumps) and the use of artificial lighting for 1991 and 1992. This research showed that the main factors that negatively influence profitability were energy consumption during cold periods and the price of tomatoes during the summer season. The conventional hot water system consumed less energy than the heat pump system and produced marketable fruit yields similar to those from the heat pump system. The hot water system was generally more profitable in regards to energy consumption and productivity. Moreover, investment costs were less; therefore, this system gives best overall financial savings. As for radiant and hot air systems, their overall financial status falls between that of the hot water system and the heat pump. The radiant system proved to be more energy efficient that the hot air system, but the latter produced a higher marketable fruit yield over the 2-year study.

The Design of Water Intake System and Analysis of Water Quality Conditions of the Regional Energy System of Complex River Water Source Heat Pump

2015 ◽  
Vol 8 (1) ◽  
pp. 38-42
Author(s):  
Pengfei Si ◽  
Xiangyang Rong ◽  
Angui Li ◽  
Xiaodan Min ◽  
Zhengwu Yang ◽  
...  
Keyword(s):  
Water Quality ◽  
Energy Consumption ◽  
River Water ◽  
Heat Pump ◽  
Water Intake ◽  
Water Source ◽  
Energy System ◽  
Sediment Concentration ◽  
Regional Energy ◽  
Heat Pump Unit

As a realization of the energy cascade utilization, the regional energy system has the significant potential of energy saving. As a kind of renewable energy, river water source heat pump also can greatly reduce the energy consumption of refrigeration and heating system. Combining the regional energy and water source heat pump technology, to achieve cooling, heating and power supply for a plurality of block building is of great significance to reduce building energy consumption. This paper introduces a practical engineering case which combines the regional energy system of complex river water source heat pump, which provides a detailed analysis of the hydrology and water quality conditions of the river water source heat pump applications, and discusses the design methods of water intake and drainage system. The results show that the average temperature of cold season is about 23.5 °C, the heating season is about 13.2 °C; the abundant regional water flow can meet the water requirement of water source heat pump unit; the sediment concentration index cannot meet the requirement of river water source heat pump if the water enters the unit directly; the river water chemistry indicators (pH, Cl-, SO42-, total hardness, total iron) can meet the requirement of river water source heat pump, and it is not required to take special measures to solve the problem. However, the problem of sediment concentration of water must be solved.

Sign in / Sign up

Export Citation Format

Share Document