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Vertical Closed-Loop (Indirect, Secondary Fluid) Ground-Source Heat Pump Systems
Published in Vasile Minea, Heating and Cooling with Ground-Source Heat Pumps in Cold and Moderate Climates, 2022
In U.S. moderate/mild southern climates, the length of vertical SDR 11 high-density polyethylene (that means that the outside diameter of the pipe is 11 times the thickness of the wall) U-shaped tubes (arranged in a series, parallel, or a combination flow pattern) is designed at between 15 and 25 m per kW of geothermal heat pump cooling capacity. The ground-coupled heat exchanger is connected to the residence by a 3.2 cm (11/4 in.) header pipe routed through the wall. Indoor plumbing includes pipe-to-hose adapters, reinforced rubber hose to and from the geothermal heat pump, valves for system air and debris purging, pressure/temperature taps on the water inlet and outlet, and isolation ball valves on the water pump suction and discharge. The pumping electrical power requirement for the small circulation pump does not exceed 0.03 kW/kW, and develops 6–9 m of water head with optimum pumping rate of about 3.2 L/m/kW. The desuperheater (for domestic water heating) delivers approximately 1.5 kW. Water was circulated through the geothermal heat pump and ground loop at a rate of 34 L/min by a 225-watt circulator pump, and the hot water is circulated through the two 170-L water storage tanks at a rate of 1.9 L/min with a 60-watt pump.
Comfort Heating Systems/Saving Natural Resources
Published in Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo, Energy Conservation Guidebook, 2020
Dale R. Patrick, Stephen W. Fardo, Ray E. Richardson, Brian W. Fardo
Electricity is frequently used today as the primary energy source for hot-water comfort heating boilers. Boilers of this type are usually factory-assembled and wired with a circulator pump, compression tank, and controls in a clean compact housing. Heat is produced by immersion resistance elements that are placed directly into the water vessel. Figure 4-38 shows a partial cutaway view of an electric hot-water boiler with the immersion elements exposed. Through sequential control procedures, different blades of the element are cycled on and off to assure even wear for prolonged operational periods. Through this procedure each element blade receives approximately the same operational time.
Heating and Cooling Energy
Published in Michael Frank Hordeski, Hydrogen & Fuel Cells: Advances in Transportation and Power, 2020
During the heating season, heat is removed from the water tank by the brine and transferred to the building at a temperature of 100 to 130°F. The system may also be used to provide domestic hot water. As heat is removed from the tank, the temperature of the water drops below the freezing point and ice begins to form on the brine circulation coils. By the end of the heating season, ice fills the entire tank. This ice is then used during the summer to provide chilled water for air conditioning. While the ice remains in the tank, the only power required for cooling is for the operation of a circulator pump and a fan.
Experimental investigation of heat transfer and friction coefficient of the water/graphene oxide nanofluid in a pipe containing twisted tape inserts under air cross-flow
Published in Experimental Heat Transfer, 2018
R Ranjbarzadeh, A. H. Meghdadi Isfahani, M Hojaji
The wind tunnel is equipped with a closed circuit in order to circulate the nanofluid, designed and built according to the figure. The main parts of the closed circuit are nanofluid storage tank, hot water circulator pump (GRS25.6–1 Taifo pump), glass flow meter (LZB-6WB) with 4% precision and measurement range between 0.1 and 1 Lit/min. The test section is a 450 mm length copper tube with the inner diameter 16 mm and outer diameter 19 mm. A differential digital manometer (Lutron PM9102) with 0.1 mbar precision was mounted in the entrance and outlet of copper tube to measure the pressure drop. The inlet and outlet temperatures of nanofluids were measured by two K-type thermocouples having 0.1°C resolution placed at the center of the inlets and center of the outlets of the copper tube respectively (thermometer sensors 13). One K-type thermocouple was also mounted before the copper tube to measure the air flow temperature. A 2000 W electric heater, a PT 100 thermocouple and a thermostat were used to control the temperature of the nanofluid in the storage tank. To prevent the heat loss in the path before the test tube, communication pipes of the system and the nanofluid storage tank are insulated.
Modelling of a water-to-air variable capacity ground-source heat pump
Published in Journal of Building Performance Simulation, 2018
Samuel Bouheret, Michel Bernier
As shown in Table 1, the heat pump capacity can be varied from 2.6 to 8.8 kW. The heat pump is able to maintain its capacity over a wide range of EWT (i.e. the return temperature from the GHX), source ΔT and air flow rate. It does so by varying the compressor frequency from 25 to 130 Hz depending on the required capacity. In Table 1, fan power is included but the power of the GHX pump and the hot water tank circulator pump is excluded. As shown by Madani, Claesson, and Lundqvist (2011), pumping power can be responsible for a large share of the energy consumption in variable capacity heat pumps, since they achieve longer operating time than on–off heat pumps. It is interesting to note the COP variation with compressor frequency. Taking the first line of the table as an example, the COP is equal to 2.8, 3.1 and 2.8 for compressor frequencies of 54, 90 and 130 Hz, respectively. This typical behaviour indicates that the COP reaches a peak near the mid-point of the compressor frequency range.
Hydrothermal Characteristics of Spinel Manganese Ferrite Nanofluid in a Metal Foam Tube: Modeling of Experimental Results using Artificial Neural Network
Published in Heat Transfer Engineering, 2019
Mohammad Amani, Mohammad Ameri, Alibakhsh Kasaeian
The schematic view of the experimental setup used in this work is depicted in Figure 2. The copper open-cell metal foam is produced by employing the casting around space holder materials approach, in which an empty copper tube with the diameter of 17 mm and length of 1 m is filled with NaCl particles with an average dimension of 2–3 mm diameter as a space holder. Next, molten copper injected into the tube to fill around the particles. Finally, after leaching out the salts using hot water, a metal foam structure is produced in the tube as the test section. The porosity of the metal foam is first determined, by measuring the dry mass of the metal foam using an electronic balance of resolution 0.1 g. The dry mass of the sample employed in this study is measured and is divided by the density of the respective material to determine the solid volume. The total volume of the sample is calculated based on the dimension of the sample. The void volume is determined as the difference between the total volume and the solid volume, and thus the porosity of foam is determined. The detailed characteristics of the metal foam tube are listed in Table 1. A reservoir made from glass has been used as the main container of the fluid. A circulator pump is provided to transfer the fluid from the main reservoir to the second one. A heating element made from nickel chrome material is mounted around the metal foam tube to apply uniform heat flux and also it is insulated by a glass wool layer to prevent heat dissipation from the surface of the tube. The tube is connected to the setup using low thermal conductivity polyurethane flanges to avoid any heat conduction. Then, the fluid enters a double-pipe heat exchanger to cool down the working fluid temperature, and afterward, it flows to the main reservoir. Nine SMT-160 temperature sensors are located along the tube surface in equal distances to measure wall temperatures, as well as two temperature sensors, are embedded inside the tube to evaluate bulk temperatures in the tube inlet and outlet. A data acquisition and computer are used to record the data from the sensors every 5 sec. Two manometers measure the pressure drop along the metal foam tube at the inlet and outlet of the tube.