Abstract: The ORNL Heat Pump Design Model is a FORTRAN-IV computer program to predict the steady-state performance of conventional, vapor compression, electrically-driven, air-to-air heat pumps in both heating and cooling modes. This model is intended to serve as an analytical design tool for use by heat pump manufacturers, consulting engineers, research institutions, and universities in studies directed toward the improvement of heat pump performance. The Heat Pump Design Model allows the user to specify: system operating conditions, compressor characteristics, refrigerant flow control devices, fin-and-tube heat exchanger parameters, fan and indoor duct characteristics, and any of ten refrigerants. The model will compute: system capacity and COP (or EER), compressor and fan motor power consumptions, coil outlet air dry- and wet-bulb temperatures, air- and refrigerant-side pressure drops, a summary of the refrigerant-side states throughout the cycle, and overall compressor efficiencies and heat exchanger effectiveness. This report provides thorough documentation of how to use and/or modify the model.

Abstract: The shell-and-tube heat exchanger (SBE), with its tubes held in plate baffles to produce cross flow of the shell-side fluid, has recently been modified to produce a RODbaffle heat exchanger (RBE) free from tube failure due to vibration. The results showed slightly enhanced heat transfer coefficients with significant reductions in pressure loss, leading to reduced cost of exchangers and in some instances smaller exchangers.

Abstract: The basic criteria are derived in determining whether the heat transfer relationship for a given heat exchanger geometry is invariant to the interchanging of shell-side and tube-side fluids. It is shown that the total heat duty, LMTD correction factor, and other indices of exchanger performance remain unchanged for a stream-symmetric exchanger when the two flow streams are switched, provided the overall heat transfer coefficient is not changed.

Abstract: A method of regulating a heat pump (2) having a variable-speed drive motor, in particular a heat engine (1), and using a cold source (4) with limited heat flow which is insufficient to meet the maximum heat requirements of a heat utilisation network (14), which are the function of an open-ended quantity (Te), is characterised in that two distinct modes of regulation are applied in sequence, the first mode of regulation being conventional control of the speed of the motor (1) by the open-ended adjustment temperature (Te) and taking effect when the heat requirements determined by this open-ended temperature do not exceed the capabilities of the cold source, and the second mode comprising increasing the inlet temperature (Ts) of the heating network (14) in a manner such as to reduce, in a controlled manner, the coefficient of performance of the heat pump.

Abstract: Efficient step (discrete) heat exchangers have been constructed. These heat exchangers approach the performance of perfect step exchangers having infinite surface area in that two step exchangers yielded a mixing chamber temperature, T m , of 11.6 mK as compared to the theoretical prediction of 6 mK. Four step exchangers gave T m of 6.6 mK. These heat exchangers are simple to fabricate, are inexpensive in material and labor costs, are reliable and perform well, and have useful thermal grounding features.

Abstract: In the solar field the ASHRAE Standard 94-77, ref. 1, has formed the basis for the testing of thermal storage devices on the basis of thermal performance. However, the application of this Standard on a prototype phase change storage device has been found to lead to meaningless results. Therefore it is the intention of this article to review the procedure as applied to an ideal fully mixed sensible heat store powered by an imbedded heat exchanger, without internal capacity and thereby demonstrate that the Standard (a) fails to correctly identify the loss coefficient, (b) is confused and confusing as to the form of the loss term during a charge test, (c) fails to identify the heat exchanger effectiveness necessary for modelling and system performance, (d) is incorrect in its assumption of zero loss during a discharge test.

Abstract: LBL has constructed a facility for testing various performance aspects of residential air-to-air heat exchangers When used in conjunction with a mechanical ventilation system, a residential heat exchanger permits the adequate ventilation of a residence while recovering most of the energy normally lost during ventilation By constructing or retrofitting a home so that it has low natural infiltration rates and by using a heat exchanger-ventilation system, a homeowner can save energy, reduce heating and cooling costs, and prevent the buildup of indoor-generated air contaminants Results obtained on five different residential heat exchangers are presented The performance criteria and the test facility are described The performance parameters measured were heat exchanger effectiveness (a measure of heat transfer ability), airstream static pressure drop, and fan system performance The performance of the five heat exchangers differed greatly The ability to transfer heat ranged from 43% to 75% of the theoretical maximum The resistance to air flow varied by a factor of two One of the heat exchangers was highly susceptible to leakage between airstreams and one had an unstable performance In the future, additional heat exchangers will be tested, a new test system will be used to measure cross-stream leakage, and the possibilitymore » and consequences of freeze-up within the heat exchangers will be investigated« less

Abstract: A description is given of a method for controlling a controllable heat pipe which has a heat transfer zone and a control zone. Constructed between the heat transfer zone and the control zone is a duct through which only the vapour of the working medium, but not the condensate of the working medium, flows. The temperature of the control zone is controlled by means of an external heat source in order to control the amount of working medium present in the heat transfer zone, so that as a result at least one of the characteristics of heat transfer capacity of the heat transfer zone, temperature of the heat transfer zone and internal pressure of the heat pipe is controlled. In addition, a method for controlling a conventional heat pipe is described.

Abstract: PURPOSE: To enable stable operation of a group of change-over type heat exchangers to be achieved by an arrangement wherein the temperatures of the group of heat exchangers are kept in equilibrium and the dry ice deposited on the heat transfer surfaces of flow paths which are changed over every constant cycle is removed effectively by sweeping air. CONSTITUTION: In a reference heat exchanger 10a, the outlet temperature of reheat gas stored and up-dated in a control device 30 is compared with a value wherein the difference between the outlet temperature of the air as a raw materials and the inlet temperature of the return gas satisfies the sweeping air temperature difference. If there is a difference between them, then a flow control valve 22a is regulated by the control device 30 to change the flow rate of the reheat gas to cincide them. In other change-over type heat exchangers 10b and 10c, the outlet temperature of the reheat gas detected by the reference change- over type heat exchanger 10a is set as a control target, and respective flow control valves 22b and 22c are regulated to vary the flow rate of the reheat gas thereby preventing imbalance in temperatures of the group of change-over type heat exchangers. COPYRIGHT: (C)1983,JPO&Japio

Abstract: PURPOSE:To improve the heat exchanger effectiveness, reduce the amount of used water and simplify the equipment by a method wherein the air is heated by the heat of the underground water sprayed in a chamber, and said air is used for heating. CONSTITUTION:The underground water is sprayed in an inner vinyl house 1 and an outer vinyl house 6 from sprinklers 3. Then, when the air is sent to the place to be heated by driving a fan 4, the outer air from a suction port 7 is passed between the inner and outer vinyl houses 1 and 6 and moreover sucked into the vinyl house 1 through a suction port 5. On doing this, therefore, the sprayed underground water and the air contact with each other directly or through a polyethylene film 8, so that the air is heated and sent through the fan 4 to the room to be heated. Thereby, with a simple equipment, the heat exchanger effetiveness is improved, and the amount of used water can be reduced.

Abstract: Wet surface heat exchangers such as cooling towers and wet plate heat exchangers are important in air conditioning A linear approximate model of wet surface heat exchangers is proposed The equations of the model are rearranged, enabling solutions for wet bulb depression and wet bulb temperature to be obtained independently, by analogy from published solutions for dry bulb temperature in dry surface heat exchangers Performance predictions by this method for a crossflow cooling tower are found to agree with those from a prevous finite difference solution Published performance measurements for a crossflow wet plate heat exchanger are lower than predicted by the method possibly due to poor wetting or excessive water flow Excellent performance is predicted for a proposed regenerative evaporative cooler using such an exchanger